This section could also be called "Don't be that guy/gal." Whether you are in a hypercompetitive league or just trying to have some casual fun, you want to be a responsible fantasy football manager. Generally speaking, that just means follow the golden rule, treating others the way you'd want to be treated in your league. With that in mind, here are some things to keep in mind, so you know what should be expected of every fantasy football manager.
Be on time for your draft. In fact, be early, just in case you're having internet issues or something else slows you down. You don't want to make everyone wait or have your team autodrafted because of the lack of time management.
Never quit. This seems simple enough in Week 1, when everyone has a chance and the future looks bright. But when it's Week 10 and your injury-riddled 1-9 team has no chance of making the playoffs, it can be tougher to continue making waiver claims, setting your lineup and responding to trade offers. Put yourself in the shoes of a manager who is competing for the final playoff spot with the team facing someone who has thrown in the towel already. If he/she tanks the game by not doing his/her part, it could affect the outcome of the entire season.
Don't collude. Collusion in fantasy sports means that two teams make a trade or finagle the waiver wire to give one team an edge in the league. There is nothing worse in fantasy, because it completely destroys the league's integrity. There are safeguards you can put in place -- getting trustworthy people in your league, having a principled commissioner, using the veto system -- but just be sure you are doing your part to avoid making transactions for any reason but improving your roster.
Don't bombard managers with ridiculous trade offers. Sometimes one person may think a trade offer is horrible and the other person may think it's legit. That's normal, and you shouldn't hesitate to make lowball offers if you intend to up the ante to actually pull of a deal. But people who send gobs of horrible trade offers typically get shunned, rarely complete meaningful trades and sometimes get booted from the league during the offseason.
Don't take forever to respond to a trade offer. While you don't have to accept, decline or counter a trade offer immediately, it is common courtesy to at least drop the other manager a line as soon as possible to let him/her know you are considering it. It gets mighty frustrating when you make an offer to someone, only to wait, and wait ... and wait.
Make your league payment on time. Your commish has enough responsibilities without have to chase you down for your payment, if you play in such a league.