1. Don't derail a discussion. Even if it makes you personally uncomfortable to discuss X issue...it's really not about you or your comfort. It's about X issue, and you are absolutely free to not engage rather than try to keep other people from continuing their conversation.
2. Do read links/books referenced in discussions. Again, even if the things being said make you uncomfortable, part of being a good ally is not looking for someone to provide a 101 class midstream. Do your own heavy lifting.
3. Don't expect your feelings to be a priority in a discussion about X issue. Oftentimes people get off onto the tone argument because their feelings are hurt by the way a message was delivered. If you stand on someone's foot and they tell you to get off? The correct response is not "Ask nicely" when you were in the wrong in the first place.
4. Do shut up and listen. I cannot emphasize enough the importance of listening to the people actually living X experience. There is nothing more obnoxious than someone (however well intentioned) coming into the spaces of a marginalized group and insisting that they absolutely have the solution even though they've never had X experience. You can certainly make suggestions, but don't be surprised if those ideas aren't well received because you've got the wrong end of the stick somewhere.
5. Don't play Oppresion Olympics. Really, if you're in the middle of a conversation about racism? Now is not the time to talk about how hard it is to be a white woman and deal with sexism. Being oppressed in one area does not mean you have no privilege in another area. Terms like intersectionality and kyriarchy exist for a reason. Also...that's derailing. Stop it.
6. Do check your privilege. It's hard and often unpleasant, but it's really necessary. And you're going to get things wrong. Because no one is perfect. But part of being an ally is being willing to hear that you're doing it wrong.
7. Don't expect a pass into safe spaces because you call yourself an ally. You're not entitled to access as a result of not being an asshole. Sometimes it just isn't going to be about you or what you think you should happen. Your privilege didn't fall away when you became an ally, and there are intra-community conversations that need to take place away from the gaze of the privileged.
8. Do be willing to stand up to bigots. Even if all you do is tell a friend that the thing they just said about X marginalized group is unacceptable, you're doing some of the actual work of being an ally.
9. Don't treat people like accessories or game tokens. Really, you get no cool points for having a diverse group of friends. Especially when you try to use that as license to act like an asshole.
10. Do keep trying. Fighting bigotry is a war, not a battle and it's generational. So, keep your goals realistic, your spirits up (taking a break to recoup emotional, financial, physical reserves is a-okay), and your heart in the right place. Eventually we'll get it right.