I am trying to paint my front door and trim. I used Kilz primer and Behr Premium Plus int/ext Hi gloss enamel. Using a decent quality brush and it looked terrible. Then I used a roller. It still looked terrible and the white seems to have whiter and not too white areas. Any ideas what my problem is?

I'm slowly finishing my basement and there is one area that is just going to be walled off and remain as unfinished storage. It's poured concrete walls and slab. Some areas were previously painted while others weren't. I once lived in a town house where it seemed like the owner just went down and sprayed everything over in a generic gray. This included the ceiling joists, walls, floor and anything else that was around. I want to do something similar. Have a clean painted area (floor, walls, ceiling), but I want to make sure I'm doing it right. Should I be worried about spraying utility items like wires and piping? What kind of paint should I be using? I was thinking just a grey primer would do the trick. Is spraying really the better option or should I roll/brush or some other option?