There was an article here last year on "Tier Drafting". This is a position scarcity strategy, but it's a little bit more detailed. Basically, rank all of the players at each position, and then organize them into tiers, between which there is generally a large drop off.
At first base, I have Albert Pujols and Todd Helton in the 1st tier. For catchers, Posada, Pudge, Javy, and Piazza are tier 1. At SS, Arod is 1st tier alone, and at RP Gagne is alone in the 1st tier.
Usually, I have about 5 tiers per position, 7 or so for OF, 9 for SP, with the lower tiers (higher-numbered tiers) being larger. I might have 20 or so 7th tier OF's, although my object is not to really draft any of them.
Then, when it's your turn to draft, you pick based on the positions you need with the fewest players in the highest tier left. Personally, I go for hitters first as well, which means the best available player has to be Arod.
If it's your turn to draft in the 5th round and there is one 2B available in the 2nd tier, and three 3B available in the 2nd tier, you'd take a 2B, all things being equal. This insures that you get the best value for your pick, compared to other players that may be available. If there's a great OF available, but there are 6 other OF's available with similar value, you can afford to wait a round or two before you pick one of them.
As far as catchers go, since no one catcher stands head and shoulders above the rest, you can wait a long time before you have to pull the trigger, even if you want a 1st tier catcher.