It's as simple as getting out of your house more often and spending more of your spare time among other human beans.
Go to gym, you'll get in shape and have more energy, plus you get to oogle at sweaty /fit/girls.
Buy a dog, they're loyal and adorable, and they provide an easy way to break the ice with anybody, if the girl also has a dog there's an instant connection there.
Join a cooking class, it's a very useful skill and it will save you money on the long run.
Take bartending lessons, it's not a very useful skill but it's fun and comes in handy during parties.
If you have brass balls and an immunity to cringe then take dancing lessons.
If that's your cup of tea then start going to the gun range, master trigger discipline, improve your aim, learn about your state's ever changing gun laws.
If that's also your cup of tea try church, bible studies and whatnot, faith brings people together.
Or you could also try the nerd version of all this, conventions, comicbook stores, friday night magic, join a tabletop rpg group, larping and so on. But I wouldn't recommend it.