I first saw this project on Pinterest, but the original how-to can be found on
this awesome blog. So here's my step-by-step account of how it all went down when I actually tried it.
First, start with a cheap thrift store painting. The one I bought is actually one of those old prints that's a stiff piece of board and has a uniform texture all over it. I wish I would've found a paint-by-number, but this did the trick. It was $4.00:

Next, go to the store and get yourself a pack or two of vinyl letter stickers. Since I don't live by a craft store, I had to go to the hardware store. Translation: NO good fonts. :(
Make sure you get the letters that are part of a white rectangle rather than the peel-off letters that are already shaped like the actual letter. If you get the white rectangle type, you'll be able to trim the letters to actual size while the backing is still attached for easy layout planning! You won't be able to do this with the letter-shaped type.

The bad news if you do it the way I did it is you'll have to cut out each letter. But it's easier in the end, I promise! Here is a pic after I had cut out some of my letters. All of the stickers in this photo still have the backing attached so I can move them around freely:

These stickers are three inches tall (in case you're wondering!). One of the problems I faced happened when it was time to place the sticker down for good. If I put a sticker down incorrectly and had to lift it, it would pull off some of the print. See next to the "T" after I had moved it to the left a bit:

Ok, now if I was going to cut ALL these letters and paint the whole thing only to find out at the end that the whole original print was ripped off when I removed each sticker, I was going to lose it. What worked for me was sticking the letter to my hand a few times before I put it on the painting:

Just take it on and off your hand a few times. It will still be sticky, and will also make for easy lifting without ruining your print! I didn't lose any more of the print after using this method. Remember to remove the stickers gently and slowly just in case!
Time to paint! Make sure you get spray paint. That means no brushes and less chance of bleeding under the stickers (though mine did bleed a very tiny bit in some spots). It would've been WAY worse had I used regular paint and a brush!

It took three coats before the original print was covered to my liking. I used a satin finish. Defects and problem areas are always accentuated with gloss, and I didn't want completely flat paint, either. Let the paint dry. Ok, time to peel off the stickers and see if this worked:

Success so far!! Well, except for the fact that I didn't use a ruler or a straight line of any kind and just guessed where to put everything. Plus, before you paint it and your letters are on top of the busy print, it's really hard to see where some of your spaces between words and letters are just too big. Darn! I can't go back now, so I have to live with a little sloping and crooked letters and the bottom words being too far apart from eachother:


Overall, I'd say the project was a success, but next time I'm using a ruler! Some of the big spaces and crooked parts are going to bug me forever.
P.S. This is a lyric from a song called "As We Go Along" sung by The Monkees (written by Carole King/Toni Stern).