thanks WOlf Knight & WoT!
WK, no secret/special technic,
just very careful masking(make sure they stick very well or you'll find paint seeping underneath..i use those very thin and narrow Tamiya masking tapes)
and good spray(fine and regular 'mist' and dont use until the last bit in case big blobs or spluttering paint spoils your last coat)...again i use Tamiya and other Japanese modelling spray cans(cant afford and not worth buying a spray-gun since i'm only spraying very tiny parts and once in a blue moon
as always, spray in a sweeping motion (yes, you'll waste a lot of paint but thats better than having thick paint running down your klicky) AND letting each coat dry before spraying the next coat...depending on the color and the base color, you may need 5 or more coats (if youre planning to spray bright red on a black surface, you might like to spray a white layer/base first)
oh, I almost forgot, remove the masking tape before they totally harden or you'll risk tearing/lifting out the paint like a skin.
like cooking, you might have all the ingredients and directions but its just practise and practise(be cautioned:I dont know how to cook, btw
)