By far the biggest piece of advice I can offer is to focus on creating a badass life that you actually want to live. Whatever that means for you. If you do that, you'll be overwhelmed with opportunities to make new friends and date cool girls. One of the most awesome things about our modern society is that it's easy to find a tribe. Whether that's church, bar-hopping, Dungeons & Dragons, running, playing sports, gardening, watching movies, or attending science lectures.
Just nerd out on whatever is your thing and with a little effort you can find a group of people who would love to have you.
What DOESN'T work, in my observation, is trying to meet girls at church on Sunday when you'd rather be playing golf. Or joining a run club because it's a good place to meet cute fit girls but you actually hate running.
This probably sounds like common sense but I've seen a lot of really toxic relationships start and end because people were "trying to meet people" rather than being honest about the type of people they wanted to meet.
A few tips that worked for me. I had tons of fun being social and dating and I got married to a girl I met on Bumble.
1. Live where you want to be social.
Maybe the best thing I did was pick an apartment near my favorite hangouts. Once I made friends or met girls, it made taking advantage of those relationships really easy because I was always physically right where we would be meeting up. Any time I got a text from friends who were in the neighborhood I didn't have to decide whether I wanted to deal with driving half an hour. Just had to walk down the street.
2. Take charge.
Be the person who makes the plan. Start the team, found the group, throw the party, whatever. A lot of my most fun memories were from events that I put on. A big part of my social circle came from starting a team in a bocce league. My wife made a bunch of her friends by starting a Bachelor Fantasy League. People in their early 20s aren't used to having to work to make friends. In college it's kinda automatic. If you can be the dude who actually makes things happen, you'll create tons more opportunity to meet people. Also, in my experience, girls find this very attractive.
3. Enjoy your own company.
The advice above is a lot easier if you actually don't mind hanging out by yourself. It's a lot easier to make plans for yourself and invite people along then it is to make your plans depend on whether anyone else wants to go. And it's also easier to invite people if you honestly would be fine going alone.
The filters are nice and help weed out people you know you won't be compatible with. 
