1. Be Happy with Your own Company
It might sound obvious, but travelling by yourself means you'll be spending a lot of times on your own. Be the kind of person who can relish alone time, and who knows going to the cinema alone means not having to share the popcorn.
2. Single Serving Friends
3. Say 'yes'
Books are vital if you're travelling alone. For one, if you're reading (or pretending to) you can eavesdrop on conversations going on around you. For two, it gives you something to do if you feel awkward about being in a restaurant alone. For three, swapping books with other people in hostels and hotels is a great conversation starter.
5. Make plans and stick to them
This gives your days some structure, especially since you've got no one else to chivvy you along, and will make sure that you don't miss out on things you want to do.
6. Or don't
7. Keep in touch
Staying in touch with people back home will help you stop feeling isolated, and you can make them jealous with all the fabulous things you're doing (or all the people you've spotted while hanging at the coffee shop).
8. Face your fears
It's not a language barrier, it's more of a hurdle, a little one, that you can knock over. If you're in a country where you don't speak the language and you're with other people, you've got a little team and you can work out what to say together.
If you're on your own, you're in charge of it all, don't worry. If you have to stand outside a shop with your phrase book psyching yourself up before you go in, that's OK. If you end up doing loads of gesturing that's ok too. If you have to point at words in the phrase book because you don't know how to pronounce them, also ok. People are mostly sympathetic and want to help you out.