Always have used lollipop sticks, and if its the wrong time of year for ice lols i use thin strips of wood with blue tac
That way you can move the models around as you primer spray then and also when you hand paint the top coats.
Fully base colour coating a 6mm minature should be no problems if you use a decent fairly stiff brush, All excess paint will be removed anyway at the same time. Then do your detail colours such as weapons, armour etc and then i always use black in wash
The only thing i never paint in 6mm is flesh faces, I leave that area as the white primer then use a skin ink wash colour and maybe black wash watered down depending on facial details of the minature
Also if putting on lolly pop sticks with blue tac ensure you leave about 10mm between each minature on the stick so you have room to get your brush in.
To be honest though i always miss bits when painting, I do it like a production run, once primed and all on sticks, i base coat each stick with the minatures on and place it to the other side of my work area. Then before moving on to another colour i will re inspect all the ones i have just painted and move them back across.
Once all are checked and are ok, then i will move onto weapons colour etc and repeat the above process,
As sometimes you just miss stuff and its a pain in the arse to get different coloured paints back out etc.
Production line painting is the way ahead especially with quality control involved or that may just be me having a bit of ocd lol