I'm also going to try stenciling with printer paper to make him a shirt. I was wondering how fool-proof it is because I ordered him a nice american apparel shirt to print it on, and I do NOT want to mess it up because it was spendy. SHould i try it first on a throw-away shirt, or will I be safe if I follow directions?
I've been stenciling for years, and it took me months to get stenciling down...unfortunately, I think that's pretty normal. But, I have some tips.
1) Don't use printer paper; buy a roll of freezer paper, it should be with wax paper and foil and stuff at your grocery store. It's paper that's regular paper on one side, wax paper on the other. Tape your stencil to the regular paper side (or print right onto the freezer paper, if your printer can handle it), cut through both layers, and then iron the freezer paper onto your shirt, wax-side down. The wax will melt to the shirt, forming a very very good bond, but when you're done you just peel it off. These are, however, one-use.
2) Use acrylic paint mixed with textile medium. These paints should be in the same place at your craft store.
3) Yes, you should practice. You don't need to practice with a complicated design, but just cut out a few stars or hearts or something and practice with those. You'll need to figure out how much paint to use, and how to apply it, and that's the tricky part. Generally, try to cover the space in as little paint as possible to cover the whole thing fully (i.e., not too thin either or the shirt shows through). I recommend using using flat-topped stencil brushes or small sponge rollers (like you'd paint walls with, but waaaay smaller, and foam). Bleeding is hard to avoid, and it does take practice. But, trust me, freezer paper is THE BEST method for stenciling on fabric. If you use a roller, try to make sure you're not rolling against the paper...a little hard to explain, but if you're stenciling someone's face for example and you're starting at the top, roll downwards over their forehead towards the nose, not upwards the hairline. This helps avoid getting paint under the stencil.
If you have any other questions, please feel free to pm me. Stenciling to your own satisfaction can be pretty hard, but I've done a lot of it, so I've dealt with most problems!