oh, man, that's an incredibly general question. Basically, do research. Browse around the cafe, look at the articles, rankings, and sleepers section, but don't take them as gospel. Look at other sites, keep up with news in Spring Training. Build up a stable of sites that you check on a daily basis. Rotoworld, Fangraphs, and Fantasy Rundown are on my list.
There is a lot of information out there and you need to just absorb it, at the same time you don't want information overload. Start with a topic and get specific. You're looking at draft prep. Do you know/understand tiered ranking systems? That's a good place to start.