All drips, and any raised spots, need to be sanded, and any holes need to be patched. All patch marks need to be sanded. If there are a lot of spots, that need sanding, it is probably not a lot more work, to sand the entire wall. Do it room by room, or you will get overwhelmed. Prime with a good quality primer, and a good quality roller. Use good quality paint, and good quality brushes, and rollers. Cheap tools, end up with a cheap looking paint job. Purdy paint brushes should work well for you, for cutting in etc. If walls are smooth texture, then get smooth texture rollers. You will still get a slight roller stipple. Thats pretty normal. Since you have never painted before, it might be a good idea, to watch a couple u tube videos, before you start.

Benjamin Moore Regal Select did badly in Consumer Reports tests due to its poor stain resistance. Behr Ultra and HGTV Home by Sherwin-Williams Showcase (sold at Lowes, not Sherwin-Williams paint stores) also tested very well. I've been using Behr Premium Plus but I recently tried Showcase in a small area and it rolled on easily. Zinsser Bulls Eye 1-2-3 is a great primer; if you are painting darker colors, use the gray version.

-- amateur

If you want to watch a great how-to-paint video, watch "DIY How to Paint like a Pro Series A to Z". The presenter is a real expert on all things DIY.

It really depends on your walls. If you have orange peel or some other texture you wash the walls, patch and retexture the patches, prime and paint.

If you are painting new walls you need to sand, prime, sand and I usually do a second prime and sand then paint 2 coats..

If you are painting walls with a level 5 drywall finish - hire a professional painter who can spray the walls.

If you are using a satin or higher gloss finish and you have a nice smooth wall you will want to sand first or if you are painting over a sating or higher gloss finish you will want to sand. You are really just de-glossing the surface.

You always need to sand patches.

If you have regular not perfect walls that you are repainting that were previously painted in a flat, matte or eggshell finish that don't have many patches or any large patches you don't need to sand. Patch, sand the patches, prime and 2 coats of paint will be fine.

A good primer and good paint won't peel.

You don't need to sand the entire wall, just the rough areas. And you may not need to prime the entire wall. You want to prime over any repairs, but a good acrylic paint does a good job of covering the previous paint color.