How does one go about making new friends....in their 30's?

Ask yourself where people that share your interests would spend their time at. Stores? Classes? Gym? Websites / forums? Meetup groups?

When you're at the place, act as if the people are friends you haven't seen in a while. Be social and friendly with everyone. Ask questions and share knowledge. Talk about your interests. After a few times of seeing and interacting with each other on a regular basis, you'll have built enough rapport to invite them to certain things if you want to.

Don't make this complicated. Just think of children on a playground. They play with others that are doing the same things they want to do (monkey bars / sand castles / slides / etc). It will only be awkward if you make it awkward. That's why I gave you the advice of treating everyone like an old friend you haven't seen in a while. Skip the introductions and just start sharing ("hey check this out" / "hey what do you know or think about this?").

 

@elevate gave a nice answer. I was asking myself the same. I think I am too weird to have friends and at my age I'm starting to accept it (31).

 

So find weird people to be friends with.

Do you really think that you're the weirdest person out there? That you're the only one of your kind?

Accept that you're weird, but also accept that it's not an excuse.