How do tennis tournaments determine where the seeds land in the draw?

Question

Obviously, #1 is at the top, and #2 is at the bottom of the draw, that's a given...but how do the rest of the seedings fall into place?
For example, the #1 seed could face the #3 or 4 seed in any given tournament.

Not sure if that makes sense.

Mike,

For this question, I'm referring to the Grand Slams, with 32 seeds.
At the French Open, #1 Henin met #8 S. Williams in QFs.

While at Wimbledon, these 2 are again headed on a collision course with Henin seeded #1, and Serena seeded #7.

Answer 1

It depends on how many players there are at the start, but imagine the chart with #1 at the top and #2 at the bottom, now put #3 1 one fourth of the way down and #4 one fourth of the way up. Then put 4,5,6,8 at the 1/8 points that are open and keep on going.
Actually, there are charts already made up with the numbers printed on them so the roughly equal players are held off from playing each other as long as possible - assuming they aren't defeated by the #67th seed in the first round. Then it is just a matter of figuring out the seeding, which is done with a computer in tennis.

Answer 2

Well, it is a system to create the "easiest" possible way for the #1 player. And then obviously the #2 is at the bottom and has the "easiest" route to the finals for his half.
Then the #4 is at the bottom of the top half, and has the "second easiest" route to the finals for that half. And the #3 player is at the top of the bottom half and has the "second easiest" route to the finals for that half.