As a gay guy, I know it can be tough to write about characters of different sexualities than you. I've sometimes had trouble writing straight men in fiction, and I've never actually played a lesbian woman satisfactorily. However, what I've learnt in my years of RPing, I think, can be helpful to everyone, should they decide to take this road less travelled.

This is not a comprehensive guide to playing LGBT characters, but here are some tips when it comes to playing LGBT characters.

1) Try to stay away from playing the 'stock' LGBT characters every time you want to play an LGBT character. Yes, there are drag queens and what're colliquially called 'flamers' in the gay community, but that doesn't mean every one of us has a feathered boa under our shirts. Yeah, there are lesbian woman that take pride in their independence and what're normally thought of as 'masculine' traits, but that doesn't mean every lesbian woman is (pardon the term, please) a 'dyke.' Nor is every bisexual female promiscuous and fake, and every transgendered person a closet case.
Of course, this doesn't mean that it's not good to play an 'out-and-proud' gay male, a cropped-haired lesbian woman, or a bisexual lady that sleeps around. However, it's insensitive to consider each one of us a stereotype, and by playing a character just by the books and by what you see on TV, it's insensitive.

While I adore Kurt Hummel from Glee (after all, he's the most fabulous one in the cast), not all of us gay guys have his fashion sense, unfortunately for me.

2) IC, not everyone's guaranteed to appreciate your character. Especially in historic RPs, homosexuality, bisexuality, and even the idea of being transgendered in America and other places was taboo (and still is today in some parts of the world). Don't throw a bitchfit in OOC that your character isn't being treated just like everyone else, because, frankly, being LGBT is being a disadvantaged minority, like African-Americans in the 1960s, Black South Africans during the days of apartheid, and women during the fight for female suffrage in the U.S. IC you'll meet some haters. Deal with IC situations the same way you would any other IC situations -- that is, keeping it IC.

3) Do not, I repeat, do not disclose the fact that your character is lesbian, gay, bisexual, or transgendered/transsexual every five minutes. Your character is bi and looking for love, we get it. You can add that info in your character sheets. But when your posts literally consists of "Hey, guys, have I mentioned I'm gay today?" I want to facepalm. Several times.

4) Think of them as more than just a sexual identity. Think of them the same way you'd think of a straight person -- as a three-dimensional person with wants, needs, feelings, thoughts, goals, dreams, and a life. We're more than just a stereotype on a page. We're just like anybody else, with the exception of who we want to sleep with at night and how comfortable we are in our bodies. I think the suicide of Tyler Clementi put this into perspective quite well -- every media source first focused on his sexual orientation and what happened to him. Only a couple days later did the reports about who and what he was filed in. He was a violinist in his ostensibly community / college orchestra. And actually, that's all I can find out about him -- every other news report is filled with the same sensationalist news reports about him comitting suicide due to having a same-sex encounter of his videotaped and posted on someone's Twitter. Who was he as a person? What did he think? What did he feel? Apparently no one cared about that, it only mattered that a gay kid jumped off a bridge.
This isn't the way any LGBT with half a mind should be portayed. And if you ever care to write anything involving a person with a different sexual identity than yours, I hope you take this notes into account and maybe even use them.

Thank you for reading this, and good luck writing!

The whole takeaway from this whole guide that I got:

1. Try not to get trapped into perpetuating stereotypes.
2. Be prepared for discrimination. Heck, you might even want to incorporate an event where this sort of treatment came to a head in their history or personality.
3. Put your character's sexual preference in the Personality field of your character, not peppered into their speech.
4. LGBT people are still people. Develop them just as you would anyone else.

Personally, the thought of making such a character never crossed my mind before reading this guide, but now I have an urge to give it the old college try. <<

I hope this is appropriate.

There's really no discernible difference between gay and straight people in my experience.

Obviously you can tell which one of these guys is gay (I'm in this.)

What a neat little guide. How queer!

^_^ Just kidding. I almost feel that I wouldn't really need to include that a character of mine was gay, even in the character sheets. I mean, I don't make a note of it that my character is straight, unless I'm directly mentioning a relationship they have/had. Not many of my characters ever develop romantically anyways, so this is really still ambiguous for most of them!

Thanks for the tips though. I consider myself rather sexually aware in real life, so it's a wonder that this hasn't translated into any of my characters. Perhaps I'll make some grizzled action heroes later on that have a sexuality malleable enough to make people wonder. And then, when they do, I won't tell them. >:D

...because, like Kronos said, it shouldn't matter.

Thank you for this ^^ but I don't think one would need help as there just like everyone else. Though the bit about not mentioning every five minutes is good :)