Sorcerer is a very good class to start playing if one wants to play a magic user, but is new to the game. He has a clearly defined spell list, from which he can spontaneously cast, which makes combat options fairly simple, particularly in lower levels.
Many people have said these things, but I feel the need to clarify and collate.
1) Not Being Hit = Win. Being hit = Loose. That means you want to:
a) keep them from getting into melee with you, or
b) make it almost impossible for them to hit you, even if they do get there, and
c) have escape plans.
Under the heading of a) the solutions are lumped under one title: Battlefield Control. Examples of this: Grease, Web, Stinking Cloud, Solid Fog, and Slow. It keeps them from getting to you, and keeps them where the tanks can beat them down.
This should comprise a significant portion of your spells known, but you want to make sure you target various weaknesses. Thus, Grease targets Reflex, Slow targets Will, and Blindness targets Fort. A combination of these three spells will make it exceedingly difficult for opponents to be able to close effectively with you, because you can pick which save you want them to make.
So if you have a charging Barbarian, you want to hit him with Slow and target his weak Will save, but Blindness will almost certainly bounce off, as it targets his high Fort save. Likewise, against a Rogue, you don't want to bother with Grease, since he'll make the save easily, but hit him with Blindness, and he is nerfed to heck and back. Likewise, don't bother trying to Slow something that casts, because odds are it's gonna have a high Will save, but a Grease might do the trick. It's Paper, Scissors, Rock... make sure you have at least one of all three, or you may not have Rock when your opponent pulls out Scissors and you get your paper cut.
Under the heading of b) the solutions are colloquially called 'buffs'. Examples would be: Shield, Mage Armor, Mirror Image, <animal>'s <stat>, Protection from Evil, and Displacement. It makes it harder to hurt you, even if they do manage to get to you.
An ideal example is Mirror Image. You get multiple images, which have a chance of being hit instead of you. So, if you have 8 images (max allowed), you have a 12.5% chance of actually being the one hit. That is before he even gets to MAKE an attack roll. Odds that he'll hit you? 1 in 8. Odds that you're about to make sure he can't try again? Much higher.
Under the heading of c), are your movement spells. At lower levels, you don't have many of these, the notable one being Expedious Retreat. However, once you get 4th level spells, Dimension Door becomes your escape route out of anything. It has NO somatic components, which means you *CAN*, if your Concentration check is high enough, cast while grappled, pinned, swallowed, clapped in irons, or otherwise unable to wiggle your fingers.
2) Not being hit is good, but actually doing something useful in combat other than not die is better. So, we have the following headings:
a) Save or Screwed.
b) No save and screwed, or even if you DO save, you're screwed
c) Party Buff
d) Blastomancy
Under the heading of a) we have our 'bread and butter' spells to use in combat when you aren't getting jumped all over. Ironically, we've covered some of these already, because they hamper the opponents ability to do much. Examples include: Sleep, Glitterdust, Slow, Finger of Death, and Stinking Cloud.
Slow is an iconic example. If they are affected, they get to only make a single standard action, OR a single move action. That means they have to close, but can't hit, meaning your buddy gets free shots. That's good. Sleep. Save or you fall asleep. In the words of Belkar, that means you get to do something starting with 'S' and ending in "litting their throats". Sure, it's also battlefield control, because it sticks them in place. But all too often, Battlefield Control is just another way to send out an SoS.
Under the heading of b) are spells which act similar to the aforementioned ones, but either don't have saving throws attached, or do things even if saving throws ARE made. Examples are: Grease, Web, Enervation, Ray of Enfeeblement, and Solid Fog. Again, note the similarities between some of these and the Battlefield Control? Yea.
So, Grease. Sure, it's got a Reflex save. But that's only if it's cast right under your feet. If you run into it, you got NO save, and NO spell resistance, and have to make a Balance check or land on your posterior. Which is not a good place to be when your friendly neighborhood tank is bearing down with lethal intent.
Enervation makes a special mention: It does Negative Levels. That's like Lose and Die all rolled into one. If they get more Negative Levels than they have HD, they die. Period. End of story. Do not pass Go, do not collect $200. And even if you don't rack up enough, they get a HUGE penalty on everything, casters loose spells, all their saves drop HUGELY (meaning you can follow up with a SoS and have much better odds of it landing), and in general, is quite possibly one of the nastiest spells to get slung at you in the PhB. Oh yea, and no saving throw.
Now then, you may notice that most of these spells will require a Touch Attack or Ranged Touch Attack instead of a save. That's nice. Touch Attacks and the Ranged versions thereof ignore armor, natural armor, and most everything else except Dex mods, Dodge mods, and Deflection mods.
To make this point painfully clear, let us use, as an example, a Great Wyrm Black Dragon (http://www.d20srd.org/srd/monsters/dragonTrue.htm#blackDragon[/url), CR 22, and not to be taken lightly. Let's look at his AC listing, shall we?
AC: 42 (-4 size,+36 natural), touch 6, flat-footed 42.
Wait... what? If I want to hit him with a sword, I need a 42. But if I only need to hit him with a ranged touch attack spell, he's only got an AC of 6? Now, this is a rather extreme example, and there are rare cases in which the difference will be nonexistent, but in general, it's a lot of fun.
Under the heading of c) we note that many of the spells (notable exceptions of Shield and Mirror Image) listed in the previous section under Buffs can be cast on others. There are others that are also fun, like Greater Magic Weapon, and spells which affect the entire party at once, like Haste, or the Mass version of the <animal>'s <stat> spell line.
In general, when in doubt, a Buff will *ALWAYS* work, but an SoS might get resisted. Greater Magic Weapon, for example, lasts for Hours/Level, so by mid-levels, you can reasonably expect your buff to last all day long. Cast this on the party tank, and his weapon just got even nicer, for free. End-Game, this can end up saving the party *MILLIONS* of gold, from enhancement bonuses you *DON'T* have to get him.
Special mention to Haste here. Your tanks get a free shot in a full attack. So the GMW before combat? Just got even better. An opening round of Haste/Slow is *CRIPPLING* to opponents, because no only are they screwed on actions, your guys are moving still faster! Thus the road to Pwnage is carved.
d) Blastomancy is doing damage yourself. Fireball, Lightning Bolt, Orb spells, Scorching ray, and Disintegrate.
Now, generally it's not very economical for you to be doing damage. A reasonable meat shield can dish out consistent damage, and you can generally nerf opponents to the point where he can do this. This makes him feel important and not left out or worthless. Also, damage output generally isn't all that good. At level 10, with Fireball, you can dish out 10d6 damage, for an average of around 35 damage, Reflex save for half, or NONE if one has Evasion. Your friendly neighborhood tank, on the other hand, sneezes that much damage by level 10, and can very easily hit as many targets as a fireball can, with the right setup.
However, while Blastomancy is generally considered sub-par, there are a couple of exceptions to this:
Disintegrate. I put it in Blastomancy, but it really is a Save or Dead spell. Basically, if they blow their fort save, you deal twice your caster level in d6's. And if their hit points goes under 0? They're a pile of ash, need a True Res to get them back in the game. In other words, they fail, they're a pile of ash. But technically, it's 'just' damage.
3) But wait! There's MORE! You can ALSO be effective OUT of Combat as well!
Yes, my friends, order now, and gain supurb Utility spells like Rope Trick, various Divinations, Summon Monster, Dispel Magic, Knock, and more!
Not every problem in a dungeon is a smelly orc trying to kill you. An impassible pit can be just as daunting. Well have no fear, my friends, because Fly can get you across, AND have use in a fight, where staying above the fray means being effectively immune to damage. When your party Skillmonkey just can't open that lock, Knock is here for you. Dispel Magic can not only be used in combat, but can also used to get rid of pesky magical traps. Summon monsters do more than provide flanking opportunities for your rogue, they can also be used to walk down suspicious hallways or open doors which are too dangerous to risk a friend opening.
Rope Trick, and the higher level version, Magnificent Mansion, deserves special note. These two spells are "I can blow as many spells as I want, because my last spell is going to be rope trick/MM so we can rest 8 hours and I regain all my spells". In other words, horridly brokentastically good. It means never having to set watches, because it is impossible for anything to jump you while 'in camp'.
Once you hit 9th level, Teleport brings a whole new dimension to Utility, bringing the entire party to wherever they want to be. When combined with Divination spells, it's called Scry 'n Die, wherin you scry your target, then teleport in, combat ready. In shorter ranges, where the party can see the target and vice versa, it's called 'Port 'n Pwn, bridging areas your opponent thought impassable. Not to mention always being able to go back to a nice, comfortable inn after a long day's adventuring, only to return to the very spot you left the night before and continue on your way.
The one fly in the ointment is that you are limited to a number of spells known, so choose wisely from these categories, my friend, and enjoy!