Looking for Advice as a First Time DM

[Aeradom]

Title pretty much says it. I'm just really getting comfortable in 5e and I've been asked to DM the next game. This particular group is more a relaxed one, basically just doing one offs that share the common theme of being part of the Assassin's Guild. The members are doing a round robin sort of thing where we each take a turn DMing and it just happens to be my turn next. I'm very nervous about doing this; bit of a procrastinator and have some ADD so it will be a challenge, but I've got a decent head start and along with general advice about DMing, i'd appreciate any particulars on my idea:

So the contract that will be carried out is a local politician locked in a neck and neck race for Mayor of the township. What the party (nor the guild) actually know is that the person who took out he contract, is the target of the contract. I thought about doing it simpler and having them just target the other guy and make it with the condition that it appear like an accident or natural as possible. But I thought, how much more unique would it be, for the guy to take the contract on himself, looking to be prepared for the assassination attempt, and then blame it on the other guy, thus causing a scandal and forcing him out of the race. I want to allow maximum freedom, so I thought I'd tell them of the target's iteniary for the next three days (and the assassination must be carried out in that window) as well as the location of his residence and let them decide how they wish to proceed.

The part that scares me the most, and is the most intimidating, is the details. Like how to stat out his security, the locations themselves where the different events will be occurring (thought one day would be a speech, second would be a enjoying an opera, and third would be fundraising dinner) oh and the "boss" persay, which is the head of his security detail. all of that just... fills me with dread trying to figure it out and balance everything.

Any help would be awesome!

[Ninja_Prawn]

Well, it sounds like you've got a good idea to work with. Some thoughts:

When you've got an open-ended problem like that, I'd advise having one glaringly obvious solution and one alternate solution built-in, as well as being open to the players' suggestions. Some people have a tendency to spin their wheels when you ask them to come up with an approach on their own.
Would the target have magical bodyguards? Wizards, animated objects, bound elementals? It might be more interesting than just guards, thugs and veterans.
Make sure you've got a good grip on the stealth rules. It sounds like they'll be needed!
Are you making your own maps? You could come up with all sorts of interesting layouts with the scenes you described - and you can put in lots of scenery to interact with. It's always nice to jump off balconies and swing on chandeliers... the picture on page 80 of the DMG is one of my favourites in the whole book.
If you've got time, have a read of this (http://angrydm.com/2014/10/the-angry-guide-to-kickass-combats-part-3-lets-make-some-fing-fights-already/). It's a great guide on how to construct a combat encounter.

[Aeradom]

Well, it sounds like you've got a good idea to work with. Some thoughts:

When you've got an open-ended problem like that, I'd advise having one glaringly obvious solution and one alternate solution built-in, as well as being open to the players' suggestions. Some people have a tendency to spin their wheels when you ask them to come up with an approach on their own.
Would the target have magical bodyguards? Wizards, animated objects, bound elementals? It might be more interesting than just guards, thugs and veterans.
Make sure you've got a good grip on the stealth rules. It sounds like they'll be needed!
Are you making your own maps? You could come up with all sorts of interesting layouts with the scenes you described - and you can put in lots of scenery to interact with. It's always nice to jump off balconies and swing on chandeliers... the picture on page 80 of the DMG is one of my favourites in the whole book.
If you've got time, have a read of this (http://angrydm.com/2014/10/the-angry-guide-to-kickass-combats-part-3-lets-make-some-fing-fights-already/). It's a great guide on how to construct a combat encounter.

Thank you for your prompt and detailed reply. The one glaringly obvious one that I was going to have is actually be at his private estate at night. They'll have 3 opportunities to go there (where as the other three are during the day and once passed it's gone) and I was also going to advise of a side quest to clean out a vault that is supposedly on the estate grounds (since they were going to have a hard time getting paid when they kill the guy who put out the hit, or at least the full bounty).

I'll tell you the one thing that scares and intimidates me the most is figuring out maps. Potentially, there's like 4 or 5 different locations involved here depending on where they want to go. I think I do want to have the estate itself figured out, but as for the rest, probably be best to wing it with those. Still, the map making part is gives me no small levels of anxiety.

[Ninja_Prawn]

Well, I'm no psychologist, but I think I would feel less anxious if I did some more prep. I'd draw all the maps and have them ready - you can always re-use them in another session.

There's no getting away from the fact that battlefields and maps are important. But fortunately, you can control them. Choose whatever layouts suit your encounters.

I'd help more, but I'm kinda burned out right now. Sorry.

[gfishfunk]

Well, I'm no psychologist, but I think I would feel less anxious if I did some more prep. I'd draw all the maps and have them ready - you can always re-use them in another session.

There's no getting away from the fact that battlefields and maps are important. But fortunately, you can control them. Choose whatever layouts suit your encounters.

I'd help more, but I'm kinda burned out right now. Sorry.

If you do want to do theater of the mind style combat, come up with descriptions of the area. Imagine some cool tactical stuff. If the players ask if something is there, answer "Yes, but -" and provide something less desirable. Often your players will come up with something interesting, and you can temper it so that it is not an auto-win button.

"Is there a place where the tunnel narrows?"

"Yes. But it dips down a bit, covered in water. You don't know how deep it is."