To weave or tie lanyards, you need three things:
1. Lanyard string. This comes in a variety of colors, usually in 100-yard spools. Any brand will work. I use Rexlace, which is around $7-$9. one spool can make a lot of lanyards though!
2. A ring. Any sort will do. You can make a lanyard without one without any problem, but if you omit one at the beginning, you will NEVER be able to get it on at the end if you change your mind.
3. Patience. Lanyards sometimes take awhile. Shorter ones can be done in an hour, while longer ones could take several. Start with a short one till you get the hang of it and are sure you wont give up halfway through.
Step 1: Getting Started
I know there are other Instructables on 'lanyards,' but all of them that I have seen use paracord, which is woven differently. It is neither better nor worse than Rexlace, just different.
First, you have to lay out your string. I recommend about a foot or two of each color (or do both the same color) on the first lanyard. This will make a keychain-sized lanyard. Cut one string, then measure it against the other for length. Lay them out in an X fashion.
Now imagine they are coming not from a common center but from the four sides of a square. Look at my edited picture. Take the one on the top right and move it down.
Follow with the one on the right bottom. Now the bottom left.
Finally, take the string on the left top and pass it over the first string, but under the second. You should now have four strings, each going over one string and under the second. Pull this tight against the ring.