Because each silk screen represents a single color from your design, it's important to plan your screens carefully. Use digital imaging software to import your design file, or scan a freehand drawing. Decide on a color palette before you buy or mix any ink. Produce a digital file with one layer for each different color. Print out a template for each layer and use these as guides when masking off your screens.
Art supply shops or websites are likely to sell rolls of silk and other printing fabric for relatively high prices. This will not only limit the amount of screens you can produce for your budget but also reduce your chance for errors and minimize your ability to experiment. Buy silk at a fabric shop where you can buy in bulk and prices are much lower. To determine whether a particular material is good for printing, apply a drop of water to the surface and see if it is able to permeate the fabric quickly. Materials that resist water will probably make poor conductors for your printing ink.
Once you've produced your screens it's always a good idea to print one or more tests on paper. This is your last chance to check registration issues and make sure each screen lines up with the others. You'll also be able to finalize your color choices and identify and seams or gaps in the screens where ink comes through unintentionally. Fill gaps with tape or contact paper to keep the image clean.
Every silk screen printer has her own method for actually pulling ink on the screen. Place a large drop of ink near the top of your screen to start. Using a squeegee, pull the ink downward to coat the entire image portion of the screen. If you pull gently, the ink will flow into the silk, but not through and onto your printing surface. Wait several seconds for the ink to settle in the silk. Repeat this motion but with more downward force, pushing the ink through the screen and onto your surface. This will give you a more consistent image than pulling only once, since it gives the silk more of a chance to absorb the ink.