Accurate location wise or hole size?
Use a center drill first, always. I have a few drills that are stout enough to punch a hole in steel without walking but my machine is also very rigid. Center drill just deep enough to get a small chamfer at the top of the pilot hole, then follow through with the drill.
If you are concerned about size you should take into account that most drills will drill slightly oversize. Look up some drill charts on the web and some of them will tell you the probable amount of oversize. If it really needs to be VERY accurate, drill the hole slightly under, then finish with a reamer.
Not sure of your application and would like to hear some other folks input but that's the way it's done here.