best way to backup my project
You could use a VCS like Git and a service like Bitbucket. This will allow you to keep track of changes, revert to them in case you screw something up, and allows you to simply clone the repository if your computer would crash. You will have to learn to use Git but if you use something like Sourcetree, this shouldn't be too hard depending on your skill level.
To add to the answer of ProtectedMode, the use of Git allows you to effectively do "incremental backups". That is, you check-in your changes locally. But now and then you do "git push", which will push all changes to a selected server. This is usually quick, as git will use compression.
I concur with ProtectedMode regarding use of git, however please be sure to use a remotely hosted git repository, and push often. If your Git repository is hosted locally, you gain no benefits regarding backup as in the event of a disk failure or catastrophic error, your data is still lost.
In the modern day of always-on internet i see no point in hardly ever pushing to the repository. Git is designed in a way that you are not required to push regularly but you can end up hurting your project if you do not!
What happens for example if you have to dissapear for 3 weeks due to a family emergency and your friends on the project decide to pick up where you left off, but they can't because it is on a local branch, which you never pushed it to the repository server?
Food for thought, i think...
Bitbucket offers free private repositories if privacy of the source code is a concern. The last company I worked with used it for their intranet application, and it's also a great way to work on the project from different computers. Github offers private repos as well but with a paid subscription.
