Go to walmart, get tshirt for 5 bucks

cheap acrylic paint for 50 cents per color.

Cheap pack of foam brushes for a dollar from dollar tree

poster board or placemat from dollar tree for stencil

Freezer paper is the best stencil material for this, you print or trace the image you want on the paper side, then iron on the plastic side to the shirt. It gives cleaner lines. But any stencil works with care. If you're up to it, go beg for a piece from the butcher at a grocery store. Tell him it's for an art project and hold some other stuff in your hands so it looks like you'll actually be buying something. Maybe actually buy something from the store if he lets you have a piece.

Here is a lady that painted several shirts for her kid. You can see the results. She interchanges the terms fabric paint and acrylic paint, but in the photos she's using acrylic. She doesn't make it clear enough that if you're using the freezer paper method, you need to let it dry completely before you remove the paper. Also, she refers to 'heat setting' the paint. She is referring to a totally different type of paint, acrylic and the fabric paint they sell at walmart doesn't need to be heat set. The kind of fabric paint they use in a professional silk screening place does, but even that is more like heating it in an oven, not pressing and iron on it.

Keep the image simple. TRUMP 2016

I made a dozen Ron Paul shirts this way back in 2008 and 12, they all looked surprisingly great. Fabric paint looks better, but the acrylic works well. It won't stand out as much as fabric paint will, so a lighter shirt with darker paint works better than a dark shirt with light paint, but that doesn't look bad, just very faded. Wash in cold water.