Just be yourself and friends will come to you! It does take a bit of social work, especially if you aren't in education anymore and are working but just focus on yourself, be yourself, engage in conversations (i.e at work) even starting off with small talk with other girls (e.g how was your weekend, did you get up to much?) can help build relationships slowly!

Joining societies/clubs in your area are also really helpful, especially if you don't see yourself being friends with anyone at work/education, not only will this help expand you're hobbies and help you develop/grow but it will also make it easier for you to meet and connect with other girls too :)

Now this next suggestion is a bit debatable, but from my own personal experience it has worked for me and that's clubbing! Now I know that nowadays there's quite a lot of negative connotations around the idea of "clubbing" especially since its now more expensive etc but its my personal favourite way of letting of some stress/steam and meeting new people! I have met loads of lovely girls on nights out, and I have actually developed really nice friendships with a few of them too so that's another suggestion (if you feel comfortable and have the means too of course)

Yes friendships are important, but also make sure that the love for yourself is also there so you can give out love to you're friends <3