You're not a robot. It's OK to make mistakes sometimes on DJ stage. However you should try to avoid all the mistakes what you can. Here are some of my advice for that.
1. Know Your Equipment
As a DJ you have to know the equipment what you play from. There's nothing more disturbing than when you stand in the DJ booth and you're looking for some function or some button and you don't know where to find them. If you don't have the DJ equipment just go to the closest store right next to you speak with the owner speak with the seller most of the times they're ok with it to let you practice on the DJ equipment. If the first one is not just go to the second one or to the third one. Someone we say ok. Once you're in try out all the functions what your DJ setup has and memorize you will thank yourself later.
2. Know Your Tracks
Really, really important to know your tracks. It's good thing to know where to switch the bass, where to start to fade in the other track, how much time you have before you know the main thing happens. It's good to know where the vocal parts are playing, when is the breakdown, where is the uplifting part, when is the climax.
3. Organize Your Tracks
On my USB stick I have like 600 tracks. imagine that if I have to go to all the 600 tracks every time when I'm looking for a certain track to play out. That would suck right? What you can do is put your tracks in folders regards by style like tech house, deep house, techno. By year, by energy level or by key. You will save a lot of time in the DJ booth.
4. Find Songs That Works Well Together
Always make some free time to practice for your next DJ set. Make sure you get crazy with the music library you have. Be brave and try different combinations of your tracks. Once you something that works well together just keep that in mind. While doing your DJ set in a party a lot of people will want to go to take a photo with you, speak to you, ask for a certain track or asks for the tracks title. In these situations is good to have these combos in mind so you know which track you will play next. You have time to communicate, time to enjoy yourself, get a drink You did good earlier and now you can just have a good time.
5. Be Focused And Act A Fool Later
it's a good thing when you finally made it to a party and you're in the DJ booth and you're kind of in focus of people's attention. You've seen all the videos on Facebook YouTube like maybe in some movies about champagne showers, throwing cakes stage-diving... Forget that. Those guys who you see in these videos has experiment in the music industry and they know how to act if something goes wrong. As an upcoming DJ I'm pretty sure you won't know what to do if something goes wrong, like the tracks just stops playing or you do a stage dive and don't manage to go back to the stage but you should start to mix your next track already. So yeah couple of things can go wrong. As a DJ your job is to entertain the crowd and you can do that by taking them to a musical journey. You can do this with proper mixing, nice beatmatching, finding good tracks that work together, bringing the energy up. Just try to do a good mixing, give your best I'm pretty sure you won't need all this crazy shit.
6. Get To The Venue Earlier
If you have time just go to the when you earlier. Something like one hour before you DJ set is a good time. You can check the environment. You can check what the DJ plays and see how the crowd reacts and you can turn this to your advantage. You can check how how the crowd reacts to that kind of music so you will know which music to play and which tracks you should not play because the DJ before you already played them out. You also have time to meet your fans, to take some photos with them, have a little bit of chit chat. Also you can meet the club's owner and the promoter. It's good to have those extra contacts.
7. Import Your Tracks Into Rekordbox
It can happen that you don't manage to acquire the knowledge of beat mixing. There are two things what you can do. You can cancel the show or you can import your tracks into Rekordbox. Once you've imported your tracks into Rekordbox make sure you set the grid points right turn on the quantize function. When you're on the stage hitting the sync function, the new CDJs it should be totally in sync.
8. Make New Contacts
It's important as a DJ and as a producer to share your work online and hit up other artists to check out your work. You can send them your original tracks, your remixes, your bootlegs, even your whole mixes and ask for their opinion. You can also check their's and leave a comment about what you think on the track. It's very important hit up other producers who're creating in your style and also DJs who play in your style, so you can send out your tracks and maybe receive some support. Who knows, maybe in the future you will do a collab together. so try to make new contacts to share your style, your music work your art.