Crossdressing For Success
I play a character of a different gender than myself about 25% of the time judging from a review of my recent past characters. I think it's a great roleplaying challenge and is a lot of fun. Of course when I GM I run female characters all the time as a routine part of any game session, too.
Though I've seen occasional forum trolls say that cross-gender RP is "weird," I have yet to meet anyone like that IRL and I've been gaming for 25 years. The majority of folks in the groups I've gamed with generally stick to characters of their own gender, but it's never been an issue for anyone when someone doesn't.
Since GMs have to play characters of another gender routinely, this tends to be an unsupportable premise anyway.
Let's look at the reasons that someone might be uncomfortable with someone else performing crossgender RP.
- Those who are so uncomfortable with gender and sexual identity in general that something so minor would cause them to flip out. I think it's fear that your character will make advances to theirs, and that if that happened it "would be really gay."
- Those who believe the other sex is weak/corrupt and shouldn't be a character in their group. Needless to say this is even more immature than #1.
- Those who complain that it's hard to keep it straight. "He's a guy, I can't think of a woman!" Of course most players don't resemble their characters in any way; they're all robots and bugbears and stuff. So that really makes no sense.
- I can't think of a single other reason.
All you can do is feel out your group. I'm not sure how to mitigate any of these concerns without being completely condescending. "Don't worry Joe, this isn't all a dodge to get into your pants?" Frankly I'd just tell them to take a drama class and/or grow up if they're "uncomfortable" with the general idea.
"You're doing it wrong"
What I see a lot more commonly is complaints that "you are playing a man/woman wrong." As in, playing to a stereotype or otherwise in a way the complainant doesn't like.
Of course, the kind of game in which people criticize someone else's character - "you're not playing a dwarf right!" "You're not playing Lawful right!" tend to be reasonably immature, having not moved past a very simplistic view of the world. In my current group, I don't think anyone would have the ill grace to tell someone they aren't "playing their character right."
But perhaps you are doing it so bad as to break their immersion. That's pretty unlikely, as the challenges of RPing authentically are unlikely to hinge on so fine a detail, but reading the As a man, how can I roleplay a woman better? and As a girl, how can I roleplay a male character better? should help you to avoid anything too egregious.
Often times, complaints about authentic portrayals are specious - I know I'd get them a lot, even when I was specifically modeling my character's behavior on a specific incident from one of my female friends' lives! "A woman would never do X!" "Well, my friend Laura did that exact thing, so zip it."
Related are claims about how "sexist" you are playing the character. Frankly, you can do anything and it be interpreted as sexist (including not doing cross-gender RP) so as long as you're not clearly trying to be a punk you may as well ignore this.