The fix wordpress malware plugin Codex has an outline of what permissions are acceptable. Directory and file permissions can be changed either via an FTP client or within the page from the hosting company.
Backup plug-ins is also significant. You want to backup database and all the files you can bring your own site back like nothing happened.
Keep control of your assets that are online - Nothing is worse than getting your livelihood in someone else's hands. Why take chances with something as important as your site?
Note that this step for setups should only try. If you might like to do it for existing installations, you need to change all the table names inside the database.
But realize that security is something you must start thinking about. Do not just be the type that is reactive, consider steps to start today, protecting see this yourself. Don't let Joe the Hacker make your life miserable and turn everything that you've worked so hard.