To maintain a wet edge, start near a corner and run the roller up and down the full height of the wall, moving over slightly with each stroke. Move backward where necessary to even out thick spots or runs. Don’t let the roller become nearly dry; reload it often so that it’s always at least half loaded. Keep the open side of the roller frame facing the area that’s already painted. That puts less pressure on the open side of the roller, so you’re less likely to leave paint ridges when doing DIY wall painting.
A fresh coat of paint makes everything it touches seem brand new. But such new beginnings cost real money. Professional painters charge around $4,000 for labor and materials to paint the exterior of a 2,500-square-foot, two-story home and roughly $5,500 for the interior. Painters’ rates may range from $20 to $60 an hour, but around $40 is typical in urban areas.
As you walk through your lighted rooms (preferably day light) see if the new coat has light spots showing the precious paint. This is call "bleeding through". This means that there's only one coat of paint or the paint was diluted or the trasition of colors were from light to dark (or the other way around) and primer was not use or the painter is inexperienced.
Lastly, chose a sheen to match the needs of the space. Flat finishes hide imperfections well and absorb light which can make the paint look darker. Eggshells and satins are tough enough to be used in family rooms, kids' rooms, and hallways but don’t hide surface imperfection well. Semi-Gloss and high-gloss finishes are primarily used for trim because they accentuate woodwork details and clean up easily.
When I had my interior painting done, after clearing out all of the furniture, myself, I also removed all of the wall plates in all the rooms to be painted. They were a beige color and probably yellowed. The wall was originally an off white and I had it painted a light-mid grey, so those wall plates would look terrible. After pricing replacement plates, switches and outlets (Would have been way too expensive to replace all of them), I decided to just paint all of the wall plates, switches and outlets (Used just a black gloss spray paint). I sprayed the plates outside and used a small brush on the switches and outlets. It worked out just fine and the blacks plates, etc compliment the wall color. It has been 7 years and the plates, switches, outlets are holding up well.