Would ordinary paint be suitable for your cream coloured plastic walls, almost certainly not.
The plastic is probably a GRP moulding with a cream coloured Gel coat layer, and needs a specialist GRP paint. There is no reason why you shouldn't do the painting, but these will be solvent based paints or two pack paints, and it's recommended that you wear a mask to protect yourself.
A few steps:
1. Make sure the plastic surface is clean and dry, you may want to use a product like "NWE Gelcoat cleaner" or "NWE Super Cleaner" - boat shops sell this stuff - around