I have been a straight ally to the LGBT movement for a very long time. In fact, ever since I could remember. My loving mothers are lesbian, and I have been on the receiving end of bigotry more times than I can count. I have faced down bullies, ran away from neo-nazi skin heads, been called a faggot more times that most. I still cringe when I hear that word, I still remember all the agony it brought into my, my siblings and my parents life.
I consider myself an ally and friend to the movement -- I have donated to causes, cried when the constitutional amendment outlawing GLBT marriage was struck down, hugged my family for almost 20 years worth of anniversaries of Matthew Sheppard's death. Fact remains -- I am a straight ally to the movement, which means it is incumbent on me to act and behave with the community in a certain way.
1) I am heterosexual -- Meaning that societal power rests with me. The relationship between oppressor and oppressed is a one-way relationship, there is no reciprocity in this relationship. There never has been. That is what it means to be repressed, that is what it means to oppress. What does this mean? My feelings as a straight dude are moot. Even if I felt uncomfortable with aspects of GLBT love and marriage (which I don't), being an ally means understanding that those feelings are expressions of that one-way power relationship. They are not inborn. They are not natural. They are passed on through societal reproduction and indoctrinated into their adherents at a very young age. The expression of these feelings into words and actions turn reproduced prejudice into bigotry. The only way to rid yourself of these thoughts is to consciously de-program yourself. Here is the thing for us people that society considers "normal" -- we start to believe it. We become afraid of people who are not normal, who don't look or act like us. It is incumbent upon us "normative" people to understand that what they have learned isn't "normalcy" its "unearned superiority". Its important for us allies to rid ourselves of these thoughts of "normal and natural" and "not normal and unnatural"...
2) When you find yourself slighted, or angry, or hurt in some way from a person in a group you are advocating for -- don't consider leaving the movement because of it! There is no reason for that! Look, here is the deal -- I introduced the oppressor - oppressed frame in the last point, but it also applies to this point. Part of the way oppressed groups cast off their oppression is by expressing their feelings. As "normatives" our feelings are always considered. By other people, by society, and minority groups are taught not to upset the apple cart or else a crack down might come down the pipe. Its all an expression of the oppressor-oppressed relationship. The members of the group being oppressed haven't been allowed to discuss their true feelings -- they are forced into closets, or know that if they do get angry they would simply be playing into a stereotype. It is extremely important to give members of oppressed groups room to express their feelings without getting hurt!
3) If someone does accuse you of prejudice or bigotry or homophobia or racism don't get offended. Learn. Understand. And if you still disagree, say so, but don't double down on your previous language. Apologize, and breathe. Nobody expects you to be perfect. There is no such thing as a perfect ally, but there are allies who learn from the groups they are allying themselves with. And isn't that the goal of being an ally? Learning about your own blindspots, learning about your own socially reproduced biases and making a conscious effort to re-educate yourself? Isn't the goal to fix the injustices you see in society? Being offended by terms like "racism" "sexism" and "homophobia" does nothing to further that goal. Learn from them! Being offended only closes your mind!
Not sure how exactly this will be received, and frankly, I don't care. These are rules I have learned through years of being an LGBT ally, and more recently, an ally in the fight against supremacy as a whole. And, of course, this isn't an all inclusive list. Please, feel free to post your own suggestions!