It wouldn't be a proper series without a roundtable. Here is some advice from the pros here at Footballguys:
The divide between "valuable in the NFL" and "valuable in fantasy football" is a key distinction for fantasy football players starting out. Whether it is understanding the scoring involved in your initial league (or fantasy football in general) or starting requirements, etc. the divide between the two subsets can eliminate a longer learning curve.
Also, blend your fandom into your team to some extent. Be reasonable to some degree in terms of how high is too high to value your favorite players, but having someone from your favorite team where they are a priority watch each week for your NFL enjoyment and also now helping your fantasy team is part of what makes fantasy fun.
Finally, enjoy the process. Every fantasy football player has plenty of growing pains as they figure things out. You may hit lightning in a bottle in your first league or season with a championship. You may finish in last place. The key is the journey, enjoyment, and learning along the way. That process is never finished. The NFL and fantasy football continue to evolve over the years. You are embarking on a fun activity which enhances the game we all know and love. Welcome aboard!