Here's my advice -- take the time to build slowly. My experience is you win on a running game grinding out yardage. Everything in the last five years has been these efforts to have huge passing plays thought the courts. But as any football fan will tell you, betting everything on the passing game is not going to get you to the Superbowl. You need depth in defense, as well as a strong running game. you need the ability to have sustained drives, as well as a depth of bench that enables you to take some hits.
Now that I've met my mandatory sports metaphor quota, let me make my suggestion for the federal agenda.
1) Modify DOMA so that it no longer requires exclusion from federal benefits of states that recognize gay marriage or domestic partnership.
Do NOT go for a full repeal. You will get nailed. You will lose big time. Go for a modification based on federalism. It is easie to get and serves your overall ends by getting a federal government you cannot trust (even with Ds in charge) meddling in things. Wait until you have sufficient coverage and momentum to come back for the bigger repeal. Go for the modification, noting that it does nothing to harm those states that wish to ban same-sex unions. It is simply a matter of basic federalism and fairness. Get some stats on how much useless time and money goes to differentiating between state benefits and fed benefits for domestic partners. Ally with breaders in domestic partnerships. Convince the conservatives it's a tax cut.
2) Permit DC to have its own referendum.
A basic home rule idea. Again, your rallying cry is simple -- let the local people decide. the opposition gets much out of the "elitist courts v. the people" meme. Throw it back at them.
3) Gays in the military.
We should be ready for this one. It is easy to document what a waste this is at a time when we need everyone willing to volunteer.
A simple, straightforward federal agenda. Winning any of these gives momentum. It isn't nearly as flashy as getting a full repeal of DOMA. But movements are not about flash, they are about being effective. That means taking a long view.