Stay in hostels. A lot of hostels will have female only dorms. This is a great way to make friends as you always end up having a chat with your dorm mates about where they're from, what they've seen in the city and what they're planning to do next. Hostelworld is my favourite site for booking my next stay!
Book yourself a tour. Many hostels will offer day trips to local sites or activities such as cooking classes. If you're not staying at the hostel, you can find other activities online! This is an awesome way to make new travel buddies and learn more about the local culture!
Volunteer. This is another wonderful way to make new friends, immerse yourself in local culture, and do some good. Workaway is a fantastic data base for connecting volunteers with amazing opportunities. You'll often receive free accommodation and a free meal or two in exchange for a few hours of help a day.
Get a local SIM card . If your standard coverage doesn't include the country you're in, pick up a local SIM card. In general, there are always people selling pre-paid cards when you land at the arrivals part of the airport. Now, if I was travelling with a friend, I wouldn't bother with the SIM as one of the nicest parts of travel is unplugging from social media and being in the moment. However, when I'm on my own- it is a huge comfort to know I can always call my hostel (or emergency services) if I need to and Google maps is my number one travel tool.