Try to provide reference material, which can consist of previously translated documents (we need the source and the target) or any documentation with specific terminology.
Try to avoid sending PDF documents as they are difficult to convert and usually there is an extra charge.
Allow enough time as rushed translations, even if they are proofread, might not be perfect, although we always do our best. Bear in mind that a translator usually translates between 2000 and 2500 words per day.
Provide feedback, as we might not be familiar with your in-house terminology, plus we always want to improve the quality of our service. With your help we can produce translations which are even better.