Version control with Bitbucket
I don't want to force a certain version control system on you, but use git. It's just great. Why? Because it's a distributed version control system which means even your local working copy will be a git server. Compared to SVN that's really awesome because you can commit, even when you're not online, e.g. driving with a train with no reliable internet connection.
Later, when the internet has you back, you can just get the changes made by others and push your changes to a kind of centralized server.
For sure, there are other reasons to use git, but this is the one I like the most. There are also alternatives to git, like Mercurial or Bazaar.
If you don't have a server, for whatever reason, there is the possibility of hosted repositories. In the Open Source world, github is one of the most used provider – it's free for OS projects but there are also paid accounts to be able to create private repositories.
There's another service, I prefer over github and it's called Bitbucket. Basically it's the same as github but even with a free account you'll get unlimited private repositories. In addition to git repositories, they also support Mercurial and every repo comes with similar features as git (wiki, issue tracking, …). The only "drawback" of this offer is, that you can only collaborate with 5 people at most – but this restriction only applies to private repos.
Of course you can upgrade to a paid subscription to get rid of this restriction.
If you're a student you're also in luck because Atlassian, the owner and maintainer of Bitbucket, has an awesome offer for you: you can sign up and request a free Academic account which allows you to collaborate with as many people as you want, effectively getting rid of the restriction ;)
As a student I can confirm that it's really useful – almost every project we work on at university is managed using Bitbucket (by our own choice of course!).
And that's not enough. Another tip for Apple OS X user: Atlassian recently bought the OS X app SourceTree, which is a free client for Git and Mercurial version control systems. Currently my absolute favorite! Maybe I'll post mor about it next time.
I hope this tip comes in useful for you. Comment if you're already using Bitbucket or planing to!