Are you bidding on those ships Alex?
First of all you need to dissasemble, remove the decals (stickers) and clean the ships in warm watter with bleach. Use a soft sponge for rubbing otherwise it will leave marks.
Whenever I want to paint something that big I get this spray paint
you can find it in various colours in many tool stores! Needs carefull use though, gentle squeeze, 20 cm distance and slow movement. You do not want all the paint to end up in one place, and clean the point after every spraying so that there is no paint dripping....