Basics about pick & place PCB design
At the risk of giving a non-answer, have you considered asking the company that will be building the boards?
You presumably have a potential manufacture in mind for these boards, if not then you probably should start looking before you get too far into the design process. Ask them what their design guidelines are.
Moving to an outside board assembler isn't just buying a PCB with parts already on it, it requires a lot more interaction with the supplier than buying a blank board and a box of parts ever does.

Ultimately it comes down to two factors - how new/high spec the manufacturers system is and how much you want to pay.

You can pack 0201 parts in like crazy but it will limit you to manufacturers who can handle them and will cost you more since you need a better pick and place machine and both yield and reworkability will go down. Or you can go for a half inch clearance around every part and fiducials all over the place and they could dust off an old machine that's been sitting out the back unused for 10 years.

Also now is the time to think about production line testability. Do you want the assembler to do any testing beyond a visual inspection? If so what testing do you want, what are they capable of and what features need to be designed into the board to aid that testing?

So ultimately find a manufacturer and ask them what their guidelines are for maximizing yield. Some manufacturers may even have footprint guidelines they like you to follow. You don't always have to follow their guidelines to the letter but everything that improves yield is a good thing.

About the only truly universal guideline is to minimize your unique part count whenever practical. e.g. If you have 10k pull ups and 47k pull ups then if possible change them all to the same value,  if you have some 5% parts and some 1% parts make them all 1%. Less reels of components that need to be loaded onto the machine will always reduce your cost.