Making arrows is the most cost effective way of course. However, as Markman8 points out, you need to have some idea of the your draw length, and the bow's draw-weight at that length. When you have that info you can make an educated guess at a reasonable arrow shaft spine, pile weight, and fletch length to use. Even then everyone who shoots has a slightly different form and loose, so if at all possible try several different sets of arrows at a safe shooting range until you find a set that matches your bow well.
Many traditional archery suppliers can help you with this, and some offer the matching service (basically a cheap rental on sets of arrows to try out at their place). Some will occasionally even waive the fee if you buy the arrow parts from them when you know what you want.
If you have a set of bathroom scales, and a stout (1x2 or 2x2) piece of straight wood around 4 feet long, you can get a close measure of the draw weight of your bow. Cut a deep notch in one end of the piece of wood. Measure along the piece of wood along from the bottom of the notch, and make a clear mark at your drawlength. Put the bathroom scales on the floor. Then, and this is a bit tricky so be careful, stand the straight cut other end of the piece of wood on the bathroom scales, and put the bowstring in the notch of the wood at the nocking point of the string. Then push down on the bow handle, keeping it close to, or sliding along the piece of wood. As you approach your drawlength mark on the piece of wood, glance down and read the draw weight from the bathroom scales, then slowly release the tension of the bow. You can subtract the static weight of the bow and piece of wood from the reading, and you should be about there.
Cheers, Bob
