Financially the best thing to do is create an emergency fund. This is typically 3 month's rent.
From there google is your friend. Cars can be a bit of a minefield but you can do basic maintenance yourself (oil, brake pads etc.). If you're really not handy with a spanner then there is no shame in getting an expert to do it (and paying for it).
Most of your friends were or are people who happened to be in the same place at the same time as you. That could be school, university, work or hobbies. It's also normal for them to come and go. Most of my friends have come from years of playing music and now more recently martial arts. Similarly you might want to join a football team, tabletop gaming group, art class, volunteeing for a charity or something else that you can share interests with others regularly.
These are very broad areas so it's difficult to hit them all, and I don't think anyone does in their lifetime. That's not a problem just learn what you can when you can and try not to get owned by life too badly to begin with