You can't just go on projections. You have to look at who's been drafted, is there a run going on, is it the end of the run, beginning of the run? How much is positional Scarcity is worth to you? It's worth a lot more to some of us than others. Victor Martinez is taken in many leagues in the 3rd. I've seen many leagues where guys like Travis Hafner, Todd Helton, Paul Konerko, Carlos Lee, Ben Sheets, Carlos Zambrano, etc are drafted behind him, That in my opinion is a bad idea. Some people overvalue closers. But you could go into a start of a season without any closers and pick up enough guys as the season progresses to do well in the category.
As far as projections go I was reading an article with a few sabermetric guys, one was Tangotiger I believe where it was said the average fan, which is most of us, can make a set of projections that are approximately 65% accurate. The best paysites some of us subscribe to are approximately 70% accurate. And they said the best guys who do this for major league teams are about 75% accurate at best. That's still a lot of room for error.
Pitchers are notoriously harder to project for than hitters. Its nearly impossible year to year to get good middle relievers who are the same you drafted last season. In one league last year trying to take pitching early I ended up with Johan Santana, Ben Sheets, and Jason Schmidt. Think back to what was projected last year, esp for jason Schmidt. Yes, Johan was his stellar self. Sheets and Schmidt ended up hurt and Schmidt in particualr pitched poorly all year. Some guys took Eric Gagne as early as the 2nd round, Keith Foulke was generally the second highest closer drafted. In another league I drafted Gagne and Foulke thinking I had saves locked up. Didn't work out too well. I find that you are much better off going with hitting early with maybe grabbing a no 1 starter and a closer in the first 7 or 8 rounds.
It all takes time, try many leagues, draft many different ways. People will swear that their way is the best, and it might be for them. As long as you are confident in what you're doing you should do well.