Start with a space that you would like to add shelves. I call this my "toilet alcove". I needed extra storage space so I thought this would be a great place.

Step 1: Measure (twice) ; )

Measure the area that you would like to add your shelves. I measured several different "widths" because the walls in my house are not exactly perfect and level.
*Measure twice, just to make sure! ; )

Step 2: Paint and Plan

I painted my bathroom for more of an added update. I planned on using some scrap wood, for the "braces" under the shelves. *see photo
The scrap wood pieces are just pine 1x4's. I drew on my walls with a pencil where I wanted the "braces" to be to hold my shelf. I used a level to make sure everything lined up. I also used a stud finder to mark where the studs in my wall were so I could drill the braces into the studs to make it more sturdy. I ended up buying the top shelf pieces at Home Depot. They are just 1x10 pine pieces. I painted the 1x10's before I put them up; I didn't paint the scrap wood until everything was up-because I was impatient. Lol

Step 3: Get to Work!

After I cut my scrap wood pieces to size, and using my level, I held them up to my pencil markings on the wall. I then drilled all (4) pieces into the studs of the wall, using 1 1/2 inch wood screws. Repeat for other shelf.
I took my 1x10 pieces and another 1x4 board (this one was straighter and prettier for some reason ?) and cut my 1x4 to the length of the 1x10's. I then nailed them into the 1x10's making a "lip" to cover the "braces". I then placed them on the braces, and Ta-da! Shelves!