I have some old rail and stile doors that I want to paint to match my trim. However, not only is there a lot of paint already on the door (probably 5+ coats), the last coat the previous owners put on was done quickly and without prepping the previous coat. So now I have some cheap paint that flakes off from time to time.

What I've done to the first door to rid myself of other lingering problems is strip all the paint off and get it down to the wood. Then I primed it and painted it. However, now the door's finish seems flat and not as durable as the other doors I have not done anything to. Is there something I should be putting on the door to help durability and help it have a little more pleasing finish than the super flat finish I have now?

Any ideas or experiences would be greatly appreciated.