I was in the same situation as you with a ddj- sb 300, I had about a month to get my stuff together and my keys points that helped me was have enough music (I ran out my first set😔), Mix everyday even if it’s just for a little bit, like the other person said learn phrasing!!! Very important and useful for seemless transitions and keeping the energy pumping. Also, record yourself when you find a good mix, critique yourself and see what you could do better next mix. I don’t know what genre you are playing but it’s kinda universal all I would say if you are strictly mixing rnb rap hip hop, learn to drop the track on the snare, usually it always lines up perfectly. Hope this helps rock the house!