As long as a translation or localization service is perceived as a commodity, it will be quite hard to emerge from the sea of competition.
The translation industry is a real strange industry in terms of client- vendor relationships. Translators send CVs instead of proposals like consultants do. The most standard unit of measure is "words", with almost no differentiation of the difficulty of the content (a real strange unit of we consider other industries). Competition is everywhere: the professional at the other side of the globe, all types of "soi-disant" SMEs suddenly thinking they could get a few extra bucks translating, not to mention the nephew of the boyfriend of the secretary who spent a couple of months abroad...
It is quite difficult to get the message accross that you are a competent and qualified professional everybody should inmediately hire before you get overloaded with work.
A long email explanation is really not the way... How long do you think the person receiving your email is going to spend deciding if you are the translator he/she would have always liked to have at hand?
There are no magic tricks. You will have to find the way to communicate, share, create interest in the kind of clients you are aiming. It requires much more effort than writting your resume or sending an email. But it may worth the effort if you want to find the right costumers.