Getting better at poker will improve your play at a given table, and should improve your profits... there's no denying that it's important. Playing position and Short-Handed play are I think major differentiators between good and great players, though, because those areas of the game are more about picking up on the information your opponents give you than the cards you actually hold, and adjusting your play accordingly.
Because of the mention of being a break-even player, my first interpretation was the desire to step up from just not losing money to making a profit. My focus is on profit, because I cashed out all the money I deposited (so anything left is profit), and have set myself goals of increasing my bankroll one way or another. If you just want to look at profit as a whole from playing poker, then I'd also add 2 more suggestions:
17) Sign up with a number of different sites and take advantage of the many sign-up and reload bonuses available (you can make thousands as a break-even player from these bonuses while still otherwise just breaking even).
18) Check out sites which offer rakeback deals, so that you can play and get a proportion of your rake returned to you at the end of each month.
My other recommendation for becoming a better, and more profitable, poker player would be to learn more of the common variants of poker. Just because HoldEm is the most popular variant, doesn't mean it's the best one for you - your natural playing style may be better suited to a different game altogether. I play Omaha Hi/Lo mostly (I find it much more profitable), and learning 7 Card Stud, Draw Poker and other variants helps in your general poker game
, because each has a facet which is more important than in other variants, and it helps you to look at different aspects of poker as a whole. That said, if you specialise in any other variant, then you have a much more limited selection of sites which are worth playing on (I'm about break-even at HoldEm now, I guess, so it's a toss-up to me whether I'm better off clearing bonuses playing HoldEm or making straight profits playing Omaha Hi/Lo), so having HoldEm as your 2nd game at least is probably worthwhile.