Painting Hard-to-Reach Areas with Spray Can?

i tend to brush paint those areas first, for example under body and axels of most warwheels. that way when i spray i don't have to worry about everybit of surface and the possibility of too much paint and runs..

Using thin tubes is a great idea!

You can use a piece of cardboard held above an area you wish to protect as a "soft mask" to prevent excess paint getting to areas where you don't want it to go.

You can extend this technique to cutting an appropriately shaped/sized  hole in a piece of cardboard and holding it over the area you want to paint.

Different nozzle styles can give different paint spray patterns from rattle cans of spray paint. Try version types, e.g., thin tubes.