A common rule in writing is Avoid Stereotypes.
While this is true to the small extent, I don't think it's 100 percent true. Don't avoid every single stereotype.
What are stereotypes?
"A stereotype is a label given to a person, a prequisite judgement." Definition number four from Urban Dictionary.
The web site also has a few examples but here is another web site for some more examples of different stereotypes: Common Stereotypes
A few examples from both sites:
Asians are good at math.
Irish people drink a lot.
Goth has to have black makeup, hair and be depressed.
Mormons are polygamists.
Gay men are femmes.
Gay women work at Home Depot.
Now, you might be wondering why I'm against the well known rule of no stereotypes. The truth is, everyone fits some stereotypes, the real issue is to not go overboard. Most people won't fit all the stereotypes but they might fit some. Even I fit into some stereotypes. Plus, the variety of stereotypes and non-stereotypes makes characters interesting. It's good to have a variety when it comes to the details of a single character, and when it comes to the overall cast of the novel, as well.
Me for example: I am from Wyoming. Don't have a farm/ranch, never been on a cattle drive, but I did take my first steps as a small child on a ranch. My dad was raised on the ranch. I date both men and women. I'm very monogamist, don't date both at the same time at all, but I did work at Home Depot not long after dating a woman. I was the femme in the relationship.
But let's look at someone aside from me. Consider gay stereotypes. Since these are the characters I write, and the people I've had a good amount of exposure too, both teens and adults, it's one I can talk about here. I volunteered with gay teens, ran a gay straight alliance club in college and took part in different events, including Pride, all while living in Utah.
Never met a gay man that had a lisp, or limp wrists. Did however, know a variety of males and females that fit within some of the stereotypes.
One of the funniest was a femme boy. He didn't like anyone messing with his hair, freaked out when he spilled something (particularly on his shirts), was a bit clutzy, very smart, loved shoes, had a female(asexual) best friend, and whenever he got excited he would speak really fast causing his voice to pitch up.
There was another teen boy who was anti-femme. They bugged him to no end and he would often rant about them to me (and yes, he was very gay himself). But he brings me to my next point...
People are contradictory.
How does this link to stereotypes? A person can fit a few stereotypes and have a few completely anti-elements as well. They don't have to make sense all the way because people are contradictory. The anti-femme gay teen is an example of that. He always talked about how he didn't like femme boys. Yet, who did he mess around with at one point? The femme boy.
The big issue with stereotypes is going too far. Don't use them all, intermix the stereotypes in with completely different elements, and a few contradictions and I'm going to bet you will have casts of very interesting characters.