Painting a commercial space is a bit more high-stakes than painting a house; your customers and vendors will see the space, so it has to look nice. If you have the money in your budget, you should definitely consider hiring a commercial painting service to paint at least the publicly visible part of the space for you. However, if you are short on funds, you can get near-professional results if you adhere to these guidelines.
Fill in Any Imperfections
The secret to getting paint flat and uniform is to make sure the surface beneath the paint is also flat and uniform. Use joint compound to fill in any imperfections, then use a scraper blade to smooth each patch out. Let the joint compound dry, and then use sandpaper to sand it down until it is perfectly smooth. Vacuum up the dust immediately so it does not end up in your paint.
Tint Your Primer
Even if the space has been painted previously, it's a good idea to apply primer as it helps hide any imperfections and ensure the previous color does not shine through your new paint. To get a better result, ask the paint store to tint your primer. They won't tint it the color of your walls—but it will instead be a nice gray or bluish tone, which helps mask imperfections better than plain white.
Use Good Brushes
One other secret to professional painting is using the right brushes. One-dollar brushes from the dollar store won't do the trick. You need a high-quality wall brush for cutting in the corners and another trim brush for the trim. Trim brushes have angled bristles, and wall brushes have flat bristles. Plan on spending at least $20 on a good brush—anything that costs less than that is not likely to be good.
Roll the Walls
Do not use a paint brush for the entire project. Instead, cut in the corners and edges with a brush, then use a roller brush for the large, flat areas of the walls. Roll in multiple directions, as this helps avoid "lines" in your finished product. And make sure you're using the right roller for your wall texture. Smooth walls call for a low-nap roller, whereas highly textured walls call for one with longer fibers, such as 1/2 inch.
With the tips above, your commercial space should look stunning—even if you're not able to hire professional painters.