First session: How can I make it a good one?

[Laughingmanlol]

In a few weeks, me and some friends are planning to meet up and play Pathfinder. No-one has that much experience of the system, but they all seem pretty keen, and I've volunteered to DM. What advice do you have, in terms of plot, combat, houserules, or other general tips, to make it a good session?
Plot:
Your group has been commissioned by an anonymous client, apparently an elderly and wealthy mage, to retrieve an object of great sentimental value to them and deliver it to a location of their choosing. They are offering payment of 200gp per person required to retrieve it, and have already provided 50gp for expenses, in addition to a compass enchanted to point towards the object, which is the staff the wizard owned in their youth and seeks to reclaim. The catch is, the staff seems to be located in the Blightwoods, a seemingly-supernatural region infamous for the twisted creatures that sometimes emerge from there, centred on the ruins of an old tower that once belonged to a wizards' circle, and to find it you'll have to deal with the creatures and phenomenon there to get to it.

Characters:
Elf Ranger - planning on becoming an arcane archer
Elemental bloodline sorcerer - wants to be blasty
Dwarf fighter - built with a tanking role in mind
The other few say they'll make characters on the day.
What I plan on including:
A social challenge or two - something to show them it's not all murderhoboing, such as negotiating with a patrol to let them enter the forest
An open-ended problem - I'm thinking a river crossing would encourage them to be creative and use their characters' strengths
Introductory combat - starting with undead for the basics, then goblins so they have to adapt to enemies with tactics and traps, then magically-enlarged and enhanced vermin like giant spiders and rats to show magical effects and poison
Introductory dungeon-crawling - in the cellar of the collapsed tower, looting the winecellar and the storeroom while searching for the staff and dealing with the aforementioned vermin
A boss battle - some suitable large monster plus minions to harass them
Potential for continuity - I'm thinking the staff the mage wants is a prototype scaled-up eternal wand that works for anyone, regardless of magical ability. When the mages realised that their creation could democratise magic, they staged a magical disaster to destroy their research, which the players can find fragments of, but now the contracter's peers have all died, she wants to reclaim it for her own purposes

My main questions are, what would make a good boss fight, what could the wizard's purposes be, and is there anything more I should add?

[BRC]

Some general tips.

1) Remember that you, and everybody else, are there to have fun. Keep that as your primary goal, above everything else. If you've thrown the rulebook into the fire and turned the entire session into a group-improv session with occasional dice rolling it does not matter so long as everyone is having fun.
2) Keep an eye on the clock. It may seem like it dosn't take very long for six people to roll dice and compare numbers, but gameplay, especially combat can drag on and on. It's impossible to predict how long things will take, but keep an eye on the clock. If need be say "We'll finish this next week" or skip an encounter.
3) DMing is Theater. Oh don't get me wrong, it's also math, and preparation, and coaching (Especially with new groups), and refereeing, and subtle social engineering, but it's mainly theatre, specifically a bizzare mix of Scripted and Improv. The image of the DM sitting behind the screen, monotoning out room descriptions is not what you're going for. The best DM's get really into it, they do funny voices, they stand up to physically act out motions in combat, sometimes they wear funny hats. Engage with your players.
4) This ties into #2 and is especially relevant for a new group. Try to minimize time spent digging through rulebooks. You guys WILL forget rules. If it's not a basic rule, or somthing you can look up quickly, don't be afraid to arbitrate a ruling for now and figure out what you were supposed to do later. Keeping the game flowing is essential.
5) Snacks. Not neccessary, but always good. They will get eaten quickly however.
6) Don't fall in love with your plan. Your plan is a blueprint drawn by a half-blind architect who dosn't know how many bricks he has to work with. If the PC's go off your plan don't try to force them back on, instead Adapt the plan. All but the most irritating groups will happily bite whatever plot hooks you dangle in front of them.

[Tvtyrant]

Rescuing a hostage covers most of those. They have to follow the kidnappers, plan how to get the kidnappe out, and fighting the enemy boss when they try to stop you.

[Xunthrae]

When I was getting ready for my first session Dming someone linked me this thread, it helped immensely, so I feel like i need to pass it on. Granted, It's made with 3.5 in mind, but it is broad enough to work with any system. I hope this helps! http://www.giantitp.com/forums/showthread.php?t=76474

[vendur]

Really depends on your friends. I have some who would have zero fun if not within 5 minutes of the campain they havent strewn the floor with some creatures corpses. Some want to take every oppourtunity to roleplay, even to the detrminent and sometimes death of their characters.

At the end of the day you know your friends better than we do. And also at the end of a day, the amount of enjoyment fun you have on a campaign is 90% a combination of the players/Gm interaction and only 10% the crafted campaign itself.

[Laughingmanlol]

Great, thanks for all the tips! I think a backup plan for exposition and prepared encounters for if they decide to just kill everyone are an excellent precaution, given it's their first game. Are there any suggestions for the more specific things, like a good 1st-level boss battle to round it off, or motivation for the Wizard to want the eternal staff?