Well,
firstly I would learn how to use a Darby and Feather edge successfully, you can fill 90% of the hollows with those without even picking the trowel back up, just roll the render back on and use a lapping action as you go. If you get my meaning.
Also I would recommend filling any initial hollows first, then apply a tight scratch coat to unify the suction also please key it properly; it is one of my pet hates to see the scratch coat with names written in or just not uni-formally scratched. It does make a difference to the top coat especially if you need to get on it early with the float .
ALWAYS top it with a light sponge to make it perfect. I use a Gyproc jointing sponge in a very very light figure of 8 motion so as not to upset or pull the render, but thats just me.