I am in agreement with many of the statements above. There are very few teams in D.V who understand / manage gameshape and enthusiasm. In my opinion, those two are HUGE at D.IV and above. Don't try to compete with the 2/3/4 teams that are clearly better than you in your first season . .. TIE those games so you can beat the teams you need to.
I agree that getting Cup wins is big . . . but only because of the immediate $$$, but because your fans feelings about your Cup run will impact attendance all season.
Cash is King!! Develop your arena bit by bit (not big chunks) throughout the season. Try to get to the 10-12K seat range within a season or two. The attendance revenue cap for D.IV is right about $160,000 per game . . . so if you have a small arena where you are only brining in $90K per game . . . that $70K per week that you SHOULD HAVE HAD adds up fast.
Don't become emotionally attached to your players! Just because Joe Schmo was your favorite player in season 16 doesn't mean you should not place him on the TL throughout season 17 until he sells. The quality of players that you need to compete will be known very quickly after you are placed into a league . . . to the research and think about what strengths you need to get. If you have some cash now, the TL has some GREAT deals on bigs. For whatever reason, there are some really strong inside players for lower amounts of cash.
Don't underestimate passing skills. As you move up the ladder, you will play teams that have 3 or 4 very strong players on the floor. If you have high passing skills at all your positions, your team will be able to find your player who is stronger than his opponent - otherwise your guys will take their chances on long / crazy shots.
Have fun and enjoy it! Hopefully you get into a league with an active forum - that makes a lot of difference in how enjoyable the game is for some people. Continue to ask questions, try to get better and have patience with the trainees on your team. Get a mentor, someone who will work with you consistently for several seasons.