@WastingAsparagus without knowing what your experience is or how much you are charging, I can't really say if you can increase your rate or not. There are a few sites out there where translators can post their information/resume. I forget the names at this time, but I am sure a quick google search will turn some up. I just remembered that Translation Directory may be one. I know that some people post their rates per word on sites like that, so it could give you an idea of what others are charging. Also, if you have some specialty – experience with legal documents, technical documents, etc. you can generally charge more for these types of projects.

In my case, nearly all my translation-type work has come from personal contacts rather than freelancing websites. These are people who know I am a serious professional, so they accepted the rates I quoted.