Dakuda is right. The installation procedure for the floor depends on the kind of flooring you want to install. Stretching a carpet over underpad requires completely different tools and a completely different procedure than installing ceramic tiles or hardwood.
I'll tell you this, tho. Besides painting a floor, the kind of flooring that lends itself to newbie DIY'ers the most is installing linoleum or sheet vinyl. That's because there is a darn near fool proof method of doing it that requires very few tools. It does require that you have a large empty space tho, but even a front or back yard will do.
Linoleum and sheet vinyl typically comes in 6 an 12 foot widths, so measure out your room to see if you can do it with a single 12 foot width instead of with two 6 foot widths because then you won't have to deal with a seam. I've only installed sheet vinyl in bathrooms which were less than 6 feet wide, so I can't advise you on making invisible seams since I've never done it.
Here's the fool proof procedure for installing sheet vinyl or linoleum:
1. Go any place that sells wallpaper and buy enough of the rolls they're trying to get rid of to make a wallpaper pattern of your floor. Usually, you can buy single rolls for $1 each and double rolls for $1 or $2 each. Make the pattern out of wall paper and duct tape or fairly strong masking tape. Lay the wall paper upside down. If it starts curling up on you, put a pipe or something in a bathtub full of water, run the pieces of wallpaper under that pipe to get the glue wet, and then let those pieces of wallpaper dry on the floor glue side up. When they're dry, they won't want to curl up like they did before wetting them.
You don't need to make a pattern of the entire floor. A wallpaper pattern of the PERIMETER of the floor is sufficient to mark and cut the linoleum or sheet vinyl accurately enough.
The purpose of making the wallpaper pattern with the glue side up is so you can write on the wallpaper. You can label the walls and doors on the paper pattern because it'll be hard to remember what's what once you're looking at only the pattern. Also, some walls will have baseboards that you'll be removing (to cover the cut edge of the linoleum) whereas cabinets probably won't have baseboards around them, only a bead of caulk. So, you need to make the cuts for the cabinets more accurately than those for the walls since the cuts along the walls will be hidden under he baseboards. With the cabinets, you'll only have a bead of caulk to hide the cut edge of the linoleum.
2. Spread your 12 foot wide roll of linoleum or sheet vinyl out in a large area like a clean basement or garage floor, or even in your front yard if there's no wind. If you spread the wallpaper pattern out in your yard, it's best to have something stiff, like a piece of plywood you can slide along under the sheet vinyl or linoleum to mark and cut on.
Now, put your wallpaper pattern on top of your linoleum. Since the pattern was made with the wallpaper glue side up, you want the linoleum to be right side up and put the pattern on the sheet vinyl glue side up too. Otherwise you'll end up making a mirror image of the room's floor plan.
Once the wallpaper pattern is on the linoleum, the first thing to do is to align the most visible baseboard in the room with any "square" pattern embossed on the linoleum or sheet vinyl. If you don't align the pattern with the "grout lines" (for example) on linoleum that looks like ceramic tiles, then the "ceramic tiles" will look like they were installed crooked in the room when the linoleum is installed. Real ceramic tiling would be installed parallel to the real walls in a room, so you need to ensure that the most visible baseboard(s) in the real room are parallel to any embossed pattern on the linoleum or sheet vinyl.
Use short pieces of masking tape to tape the pattern down to the sheet vinyl every 3 or 4 feet to prevent it from moving.
3. Now, simply trace the pattern of the room on the sheet vinyl with a felt pen. Where you will be removing baseboards or shoe moldings (frequently incorrectly called "quarter rounds") you can make note of that on the wallpaper when making the pattern so that you can mark the wallpaper pattern edge on the linoleum, but cut the linoleum a bit (say 1/8 inch) shy of that mark to make the installation easier since that cut edge will be hidden by the baseboard or shoe molding anyhow when they're reinstalled.
4. Remove the pieces of masking tape holding the wallpaper pattern to the sheet vinyl, checking to ensure that the wallpaper pattern outline has been marked onto the linoleum all around the "room".
5. Cut through the sheet vinyl or linoleum with a razor knife. Have something like some scrap plywood or scrap plastic laminate under where you're cutting so you don't damage whatever is under the linoleum.
6. Roll the cut linoleum up and roll it out in the room to see how it fits. Make any final cuts to improve the fit.
7. Place something really quite heavy, like a spouse, on one half of the wallpaper pattern and roll up the other half of the pattern. Then, spread the recommended adhesive on the exposed floor on the rolled up side of the room, wait the required time for the adhesive to get tacky and roll out the linoleum onto the tacky adhesive taking care not to trap any air bubbles under the linoleum.
8. Move the weight to the other side of the room (that's already been glued down) and do an encore performance on the other side of the room. You can also do the room in 3 or 4 parts, if that makes more sense based on the shape of the room and linoleum you're dealing with.
In the above procedure, any embossed pattern on your existing floor will "telegraph" through to show as a "ghost pattern" on the new linoleum or sheet vinyl. For example, if your old flooring was ceramic tiles, and you installed sheet vinyl over that, then you'd see the old grout lines eventually showing through on the new sheet vinyl. Even if the old flooring was sheet vinyl that only looked like ceramic tiles, if the thickness of the old sheet vinyl is slightly less over the "grout lines", that's called an "embossed" pattern, and the fake grout joint pattern will still show through as a ghost pattern on the new sheet vinyl or linoleum.
To avoid those ghost patterns showing through, you need to spread a floor leveling compound on the old flooring to fill in any embossed pattern. I use a product called Mapei Planipatch available at Home Depot for that. You will also need the additive called Mapei Planipatch Plus to mix the Planipatch powder with. But, that's a topic for another post.
