Tips for Good Translations

Take care of spammers
Since e-mail addresses of translators are featured in .po and .mo files, translators are advised these will be used by spammers. Please ensure you are driving people to a place that is safe for you.
Don't translate literally, translate organically
Being bi- or multi-lingual, you undoubtedly know that the languages you speak have different structures, rhythms, tones, and inflections. Translated messages don't need to be structured the same way as the English ones: take the ideas that are presented and come up with a message that expresses the same thing in a natural way for the target language. It's the difference between creating an equal message and an equivalent message: don't replicate, replace. Even with more structural items in messages, you have creative license to adapt and change if you feel it will be more logical for, or better adapted to, your target audience.
Try to keep the same level of formality (or informality)
Each message has a different level of formality or informality. Exactly what level of formality or informality to use for each message in your target language is something you'll have to figure out on your own (or with your team), but YACS messages (informational messages in particular) tend to have a politely informal tone in English. Try to accomplish the equivalent in the target language, within your cultural context.
Don't use slang or audience-specific terms
Some amount of terminology is to be expected in a blog, but refrain from using colloquialisms that only the "in" crowd will get. If the uninitiated blogger were to install YACS in your language, would they know what the term means? Words like pingback, trackback, and feed are exceptions to this rule; they're terminology that are typically difficult to translate, and many translators choose to leave in English.
Read other software's localizations in your language
If you get stuck or need direction, try reading through the translations of other popular software tools to get a feel for what terms are commonly used, how formality is addressed, etc. Of course, YACS has its own tone and feel, so keep that in mind when you're reading other localizations, but feel free to dig up UI terms and the like to maintain consistency with other software in your language.