Everything else though, takes up a lot of time.
Designing the shirt. Breaking down a multi-color design into separate layers can be a huge pain in the ass, and very tedious, but it's totally worth it in the end.
Prepping your transfers. On a mulicolor design, you have to make sure that every transfer is perfectly lined up, or your design will be all wonky, and your layers won't match up. Even if you aren't working on a multi-color design, you have to make sure your screen is lined up, or you will find yourself adjusting and readjusting your shirt underneath the screen to make sure it centers well. If you're doing a run of shirts, the screen gets covered with ink which blocks your view of the shirt underneath. If your design isn't centered on the screen, forget it.
Waiting for emulsion to dry. I find myself wasting the most time waiting for my emulsion to dry on the screen because I want to get right to printing shirts as soon as possible. So I keep checking my screens over and over to see if they are dry. If you are using photo emulsion, and you aren't working on an air-conditioned environment (which I am not), it can take as little as a couple hours and as much as two days for your emulsion to fully dry, depending on the humidity levels in the ambient air. If you jump the gun and do a photoburn on a screen whose emulsion has not fully dried, you will find yourself washing most of the emulsion right off the screen, leaving a big, ugly, patchy hole in your design. And since not ALL of the emulsion comes off, you still have to clean the screen, wasting emulsion remover and time in the process.
Waiting for Ink to dry I use an artist quality fabric ink, as I dont' have the facilities for a big professional operation with plastic inks or a flash burner to solidify my ink. So I have to wait for the ink to dry. Usually 24 hours for it to fully dry. Then, after it has dried, I have to heat seal the ink to the shirt. I use an iron. The idea is to iron the shirt until you see smoke coming up from the ink, but without burning it. Depending on how big the design is, that can take as little as 5 minutes, or as long as 30 minutes, doing the shirt in sections. The worst thing that could possibly happen is that I miss a spot, or I don't iron it for long enough, and the ink ends up washing right out of the shirt when my customer washes it.
Shipping It's about a 30 min ride to the post office and back.
And then, I'm done! Until I get my next order...