just be logical and carefully work your way through everything.
did it run just before you did the work or are we talking a couple of years ago ?
if you have got photos of cams and your own markings then check these first to make sure you have the correct cams in the correct place and the pulleys on the front of the cams in the correct place .be 100% sure, just take your time and compare what you used as reference.
then make 100% sure that the belt and pulleys are timed up correctly. turn the engine to nearly tdc,fit the crank tool and carefully bring up to tdc.make sure top alignment tool shows everything ok.tweak if required and then finally check tension wheel marker pointer.turn the engine a couple more times and recheck .
watch club dvd ,youtube videos or whatever method of your choice to be sure everything is ok.
then personally i would crank the engine over with fuel pump and injector relays removed to make sure it "sounds right" if you know what i mean.you should have an evenly spinning engine with no unusual slow spots or fast spots just a normal sounding engine with even compression strokes.
after this its a case of :
are the plugs ok
are the leads ok
is coil ok and firing order correct
is the fuel pressure good,fuel new,filter ok
is everything plugged back in as and where it should be
all air hoses,vacuum hoses,servo hose connection
basically checking everything is back to where it was before you started the job
this list is largely dependant on your answer to the first question thou !