Over the years, iv'e known a ton of people with autism and aspergers and one thing I notice about many people on the spectrum is that they have poor appearance and hygiene due to not caring about how they look. They don't comb their hair, they don't shower, they don't put any effort into clothes selection or style, they don't bother working out. And the sad thing is that many of them aren't terrible looking guys, they just don't see the point of caring about how they look so others think they're ugly. The experts say autism does not affect personal appearance but too many of us don't take personal hygiene seriously enough. And as a guy who's known over 100 people with it, I definitely know this is true.
Here's the truth about life, not only does your behavior affects how people treat you but so does your appearance. It's why those with baby faces are more likely to come off as innocent, why nobody wants to hit a woman, or why nobody takes a little kid's opinion too seriously. It's also why everybody thought Susan Boyle was going to suck simply because she was ugly and plain. Whether you like it or not, you are being judged by your appearance and others are making assumptions about you even if it's sub-conscious.
There are some things about your appearance that you can't change. But there are some things that you CAN change and this will make people think more highly of you. You can first start off by giving a sht about how you look. Comb your hair, shower every single day, shave, get better clothes, get a better haircut, wear nice and fitting clothes, find a style for you. Because if you dress like a slob, people will see you as lazy, unintelligent, or not as friendly. That's why it's always important to care about how you look, I don't care who you are.
Secondly, start working out to either lose or gain weight. I know that many people with autism/aspergers dislike exercising but there are so many health benefits to running or working out with weights. For one thing, you're going to get a better body and this will make you feel better about yourself and as a result you will become more confident. Also, aerobic exercising increases the hardness of your erections and releases endorphins which helps fight off stress.
Nutrition is equally important. There's an old saying that your body will treat you the same way you treat it. If all you are doing is eating junk, then your body will punish you for it but if you are eating plenty of good and healthy food, your body will reward you. If you feel like you need to gain muscle, start working out with weights and eat plenty of protein.
And even though appearance matters, it is not everything because you know what else people judge you on? Your behavior and character. You can be the reincarnation of a greek god but if you never take work seriously, or show up to work shirtless and start farting stairway to heaven do you think anybody is going to take you seriously? Probably not...
But on the bright side though, you'll probably be a hit on Youtube.