You did not give any context about the gig…club, something else, who is providing the gear, event type, audience size & age, other DJs, etc. Those details matter…but I can still offer some general advice.
A song is played for about 3 minutes…you can average about 20 songs per hour. That is a good number to use for planning. I would prep about 30 songs for each hour of the event. Double check the load point, the bpm, and grid. Listen to these songs so you can recall the details - intro, lyrics, breakdowns, loop points, mix in/out points, etc. If needed, set some cue points, or loops…depending on how you want to use that song in your set. If you have to do a handful during the event to handle requests…that’s easy…having to do half the songs you are planning to play, that’s stress you do not need.
Know what EVERY BUTTON on the S2 does. Every single one.
Setup the laptop, controller, and whatever else you are thinking of bringing…play some music. Then pack EVERYTHING you just used into your gig bag. Ask what the connection to the mixer is, and make sure you bring TWO of that cable. In fact, having TWO of ALL the cables is not unreasonable.
Have some backup music ready to go. This can be a couple AUDIO CDs, a playlist on an iPhone (in airplane mode…no calls during your set), or even a thumb drive (if you are bold and know EXACTLY how to use that on the system at the gig). There is a GOOD chance you will need to use this when transitioning from one DJ to another (if there are multiple DJs playing…you didn’t say).
Eat a meal of REAL FOOD 1-2 hours before the gig starts. No junk food. No caffeine loading. No sugar loading. ABSOLUTELY no alcohol (or anything else).
Show up early. You would rather stand around for 30 minutes ready to go, than be even 1 minute late. Setting up in a rush is stress you do not need.
KISS (Keep It Simple Stupid). Play slightly conservative…stay within your comfort zone…both in terms of song selection, and mixing. Resist the temptation to get fancy with your mixing or effects. Less is more. For your first time out, a solid set that shows mastery of the basics is MUCH better than anything else. If nothing else, this will help to reduce your stress…and it may even give you some time between transitions to look out and see what is happening in the room.
Look at the room. Watch the people who are dancing on the floor, tapping a foot in the chairs, maybe singing along, etc. Also, try to find anyone who looks bored or like they are not having a good time…then change their mind.
Finally, remember to take a few moments and notice that you are having a good time. 