1) I do not hoard my wow-bangs. If I die with a sheet full of magical items or spells, then I played in vain. I am not here to advance a character, I am here to make fun memories with people I enjoy spending time with. Regular battles of attrition are slightly more interesting uses of my time than a 3rd grade math pop quiz.
2) Getting somewhere depends on rudimentary time management. Pixel-bitching for 45 minutes on something that isn't going to change the curve is wasting not only your time but everyone else's. I know there are one-way doors in the game, but most of the time you can come back with better information if it seems like you're missing something, rather than OCD on not-immediately obvious Q or A.
3) I surprise the DM - I do not find the margins and color inside of them. I find the weak points not considered and blow up the best-laid plans of my adversaries like the dudes walking away with their backs to the explosion. I am not concerned about dramatic tension; I am looking to dominate, bypass, confound, and neutralize. Moments of sheer panic will happen regardless but my goal is to have none.
4) Help other players have big moments - I know I'm a strong personality who will end up in a caller-like role whether consciously or unconsciously. So if leading a party, be a leader-servant. When other players are all looking at each other unsure of what to do, break the silence. When other players have an idea, help them make it happen. When you see a way for them to shine that they don't - put them in that position and try your damnedest to make everyone the party's X factor from time to time. When you all get together over beers afterwards, no one wants to hear stories about one person's character.
5) Spend your damn money - buy information, rumors, contacts, hidey-holes, strongholds (name-level or not), small armies of mercs, church support, adoration from the masses, and anything and everything else that gives your DM a lever to move your world. Whenever I look at a player's character sheet - presuming they have all of the basic game necessities met (training, maintenance, whatever) - and there's some ridiculous amount of gold scratched on there I feel like I'm sitting with a middle-manager only capable of following someone else's plan. Help them see the possibilities.
6) Have a short, medium, and long term goals that have zero to do with whatever the DM is cooking up - tying in with the above, adventure seeds are great - I'm always hunting for this stuff. But surely you know something you want to do that's intrinsic to yourself. Are you a fighter that wants a magic sword? Don't pine for it, drop out-of-game hints, or anything else. Start hunting for it; make it known within the world what you seek (at least to those who might point you in that direction). If you're a thief - make contacts way before you're thinking of setting up a guild in a few levels. Look for one ripe for takeover. Cleric? Where doth the church need extending its reach? Etc.
7) Contribute to the game world - make custom spells, items, and prayers. If you're a fighter, don't just found a stronghold - find a good natural harbor and start a new city.
8) Pay attention - be ready to roll. Don't be the guy saying "huh" every time. Speak up. Move things along. Write down stuff.
9) Be versatile - every time I see a player whine because they had a specific idea for a character in mind and must have that or their time isn't fun, I get flashbacks to every high-maintenance girl I've ever stupidly dated anyway. The warning signs are always there early, and they always come true.
10) There is no arc - embrace setbacks. This is not a novel. At this point there's nothing more boring than saving the world except a nice steady progress from week to week where my character consistently waxes in power. I don't invest in the bond market, and I'm not looking to play D&D to meter my progress through the level names. You're not really winning at D&D if you never lose. Gamble. Take big risks with the equivalent of monopoly money. If you're a character-driven roleplayer, seek the admiration that comes from a populace that sees your character rise from the ashes to become even better than before the tumble. Laughing off real adversity is the role most D&D characters should be playing, not the guy who always hits their scratch off ticket for $1 more than it cost.