I have owned a few strat copies and here is what i have done.

Stripped the paint off( long and detailed but fun)
Change pickups.
Add A 9v BATTERY!(the battery will just enhance the pickups you just bought)
tuners, the locking kind
if you are going to change your trem, i would suggest a bigsby, just because they are cool.
a black pickgaurd, so you can be like David Gilmore! (he just had a black strat, and changed his pickgaurd from white to black, and left the knobs and pick up covers white. It looks very cool.)
A New neck. This might be difficult because it might not fix exactly. Measure twice buy once.

thats it. good luck have a blast.