Probably not the best idea to try to use roleplays as a medium to express social issues and values. As a writer, for a lack of better term (story teller, perhaps?), it's best to make and play characters that have merits that are their own instead of imposed values of the author. Nobody wants to get involved in a roleplay where they feel like they are being preached to, especially if the opinions are particularly hard lined.

That said, if you wanted the values you wish to convey in your characters, the best way to do that is to make them reflect the best positive traits you wish to see. My two favorite roleplay characters of mine are both female characters that don't conform to gender norms and have very strong wills and independent personalities. It helps they're in pretty gender-neutral settings, but overall they're well-developed characters that work well with the casts of characters. Their worth and ability is based off of their own merits, regardless of gender, and that is key. You don't want to more or less shove things down people's throats or become overbearing, otherwise people won't want to associate with a character (or, in extension, you). Having healthy relations with other players and their characters also goes a long way. People more or less want to do this to have fun or tell a story, and it's a lot easier to enjoy yourself if you don't feel alienated or like they're getting preached to.

To be clear, I don't know what you're like and I'm certainly not saying any of that because I think you'll be overbearing or anything, it's more or less a general statement related to the topic in general. The best thing, really, is to show, not tell. Have characters exemplify the traits and ideals you want to convey without alienating or talking down to anyone and it can be great. Just don't use roleplaying as a medium for social commentary, that's a pretty unpleasant line of thinking. Putting it another way, a lot of people use roleplaying as escapism to get away from troubles in the real world. It would be kind of like popping in a new first person shooter on your WiiStation One and being bombarded with messages from the firearms rights lobby in the loading screens or having characters look at a bunch of dead civilians and having your squad mate mournfully lament, "This would have turned out differently if only these people were allowed to conceal carry." or other such hyper-political nonsense.

On the flip side, having characters who are racist/ sexist/ generally awful is a great writing exercise that doesn't reflect on the writer if they're capable of distancing themselves from their characters and it often acts as a great contrast to the rest of the characters, who usually are much more progressive-minded and tolerant. Sometimes, being shown awful traits in a character in a fictional setting is a great way to kind of have a commentary about the real world, and it adds some delightful group dynamics and conflict to work through, and the best part is, your dick character can eventually work his or her way past their narrow worldview and expand a lot easier than somebody in real life. I mean, if the reason your fantasy party can't obtain the gemstone that can save the kingdom because Sir Douchebag of Assholeshire doesn't want some filthy elf bitch (who is the only one who can unlock its power) getting her dirty hands on it because of some deep seated prejudice that goes against all rationality is often a lot more effective at making people reflect on the issue at hand than having a character tell them about how Sir Douchebag is a real turd off handed because he thinks elves or underhanded swine and women are weak and feeble. Being able to have a context for the situation is way more fulfilling and it drives the point home in a memorable way, plus it gives the party something to work together on overcoming.