If your gonna be warmin' up and Ive done a few warmin' up sesh's with old skool b4 the main DJ, look at it like this....
Put for example 100 classics in front of ya, now you're gonna press these 100 onto 50 pieces of vinyl (pretend) - 50 A sides/50 B - sides! All the tunes you decide to put on the B-side (and remember the A-side has to be better than the B-side) will be your warm up!
You also have an advantage over all the other DJ's, coz your on 1st, so you wont get some nugget comin up2 you and sayin' 'Its already been played that!' in which you reply, 'Speak to the hand!'