Don't use iron-on transfer paper for inkjet printers in your laser printer. The heat can cause the paper to melt all over the inside of your printer, possibly resulting in hefty repair bills.

Check the box or label carefully to be sure you are getting inkjet transfer paper for your inkjet printer or laser transfer paper for your laser printer.
Special Purpose Transfer Paper
Most transfer papers are for white or light-colored fabrics. However, iron on transfer papers also come in a version specifically for dark colored t-shirts. If you are creating a design for a black or dark blue t-shirt, be sure to get transfer paper for dark t-shirt transfers. There are also stretchable fabric transfer sheets that work in inkjet printers.

While a lot of transfer papers need to be peeled off soon after ironing, transfers with cool-peel backing papers are specifically created to be peeled off after the transfers cools. No scorched fingertips!

Iron on transfers sit on top of the fabric, adhered to it by heat. They can leave a bit of a plastic-like feel where the transfer is on the t-shirt (or other fabric). When you use iron on transfer paper it's not absolutely necessary to trim the excess paper around your design, however you'll end up with a large unprinted plastic-like section on your t-shirt that can look and feel a little odd. So, for best appearance, trim close to the design before applying the paper to fabric.