Trade paint.
If you're not experienced, I'd stick to water-based. The better quality water-based ones are very good these days. Oil based gives a good finish, is harder wearing, can be applied very thin so keeps the detailing in mouldings better, and is faster to apply, but only if you know what you're doing. If you don't have a light touch and know exactly how much to brush it out it's messy and slow and you'll get a poor finish. It also takes AGES to dry.... SkankingMopoke is right about undercoats too. If you're doing water-based on oil-based, especially on gloss, either sand or undercoat or both.