I'm usually the DM, so I need to roleplay for both sexes quite a bit. I also try to use a different voice for every character if possible. IMHO, I do a pretty decent old woman/cackling witch. But it's a lot tougher to do the younger females properly without sounding too corny.
When playing, I usually play males, but have done a few females. I try to break the mold and make them each somewhat unusual, but of course that goes for all my characters. No busty amazons, or dumb blondes or sultry brunettes. Instead, here's a few examples of various females I've played:
- A rather plain, bookish female human cleric who developed strong feelings for her mentor, which eventually led to them both getting tossed out of the sect. After a series of good deeds, she eventually earned her way back into favor with her church so that she was allowed to finally build her own temple and retire from adventuring.
- A female elven wizard who was extremely bright, but who had the personality of a board. I modeled it somewhat after how I thought a Star Trek Vulcan might behave which at that time was how my group was interpreting how elves might act. This was decades before T'Pal on Enterprise. She simply let her magic do the talking for her, but was prone to do unexpected things, especially if someone pissed her off. "Why didn't you fireball them?" "Last time you said you didn't need my help." She often bordered on being a smart alec'y be-atch, yet never quite crossed that line entirely. She was chaotic good, so it was within her alignment to be unpredictable.
- A beautiful female half-orc fighter. She was a most unusual specimen given her racial heritage. She was merely trying to be accepted for who she was, yet had trouble fitting in. Most people were put off by her orc-lineage, and she always felt like she had to go that extra step to prove herself. She tried for affection at times, but that usually backfired. She got tired of overhearing the men at the inn the next day saying things like "Man, you were so drunk, you hit on that half-orc!". Eventually, a powerful devil whom the party had met but failed to defeat in an earlier adventure returned and kidnapped her, claiming her as his bride (against her will, mind you). The party was unsuccessful in saving her.