Let me get the point clear: I am not a translator, I have never step a foot into a translation agency and I know nothing about the translation business. But as a simple customer, I have had a large amount of interactions with many freelance translators (most of this experience is related to the setup of the PeopleWords website).
Good online marketing is about sending positive signals to the customers. As a freelance translator, what signals are you sending to your customers?
If I am writing this small guide, it's because I have noticed that translators, in my experience, have, on average, poor online marketing strategies. When I say "online marketing strategy", I mean What are you doing to convince a customer that you are an honest and brilliant translator. I have seen dozens of translators, often claiming years of experience for large and well-established companies, doing so ridiculous mistakes in their interactions with potential customers (i.e. myself) that I think a few "marketing" tips might not be totally unnecessary.
Sending your resume
Frankly for a $100 online translation, I am never going to read your resume. Consider that for a $100 job, I am receiving a dozens of resume. Do you really think that a typical customer is going to read 20 pages (or more) of resume for a $100 job? Additionally, there are so many resume just freely available on the web, what kind of proof is that? What tells me that you did not just get a random resume on the web and put your name on it? For online translation jobs, the usability of resumes is close to zero.
Not disclosing your personal data
What is your real name, your address, etc? Most online translators seem to be very reluctant to disclose anything. Do not expect the customer to ask you such information, you have to disclose everything first. Just consider the customer position: if you have to choose between 1) a "real" person with a "real" name and a "real" address; 2) a fly-by-night anonymous login. Who would you choose? By the way, what are the risks of disclosing such information anyway? If you are afraid of being visible on the web, surrender now all hopes to become a successful online translator. Also avoid any email@example.com, firstname.lastname@example.org and email@example.com e-mail addresses. Those e-mail providers are widely known to be totally anonymous. You need a trustful e-mail address (see point below).
Not having your own website (or blog)
A website or a blog (with some content in it) is really a strong signal for the customer. It means that you have a persistent online existence. Persistence means that you did not appear last week and consequently that you will most-probably still exist next week. The number one quality of freelance translator homepage is not shiny designs (who care's if it's just plain text) but bilingual content. Your page must be available at least in two languages. What a better proof that you're not a soon-to-be-vanished crook? Setting up an homepage requires only a few hours of work. Yet, my guess would be that more than 95% of the freelance translators do not have a personal homepage.
Poorly written communications
As a French customer, I can't judge whether you're writing good Chinese or not. I have no way to check your Chinese writing skills. Therefore, I will judge your skills based on what you will be writing to me. If your communications are constantly full of spelling mistakes, how can I trust you not having the same amount of spelling mistakes in the translated documents? My experience is that more than half of translators do not pay any attention to the spelling mistake in their communications. Spelling mistakes are a strong negative signal for the customer.
Unfocused job application
This point is connected to the resume discussion here above. A customer posting online a translation job is most likely to get at least a dozen of competitive translation offers. Therefore, your answer must be sharp and focused. Do not cut-and-paste a 10 line presentation of yourself, it's almost as pointless as sending your resume. In your answer, you must prove to the customer that you have some understanding of his context and that your experience matches his documents. In the customer's mind, such an answer sends a highly positive signal that you've already started to work on his case (which is not totally untrue).
As final note, remember that the customer choices are more a matter of trust than a matter of price.