To make a banal yet important point, if you want to make a difference on LGBT issues (or any other issues) the best use of your money is going to be donating directly to political candidates in primaries. Every election cycle, pick the primary candidate who’s better on your issue, even marginally better, hand her a check and tell her why you’re handing her a check. Call her office ahead of votes you care about to tell her what you want. And if she votes your way, write a letter to the editor of the local paper praising her. I promise you this works.
Consider donating to pro-equality Republicans too. Things are starting to turn in the suburban districts on this front. The LGBT Equality Caucus in Harrisburg now includes 3 Republicans. We need to reward the Republicans who want to agree with us on this issue. The endgame on LGBT rights has to be to raise the status of the pro-equality position in both parties, not just the Democratic Party.