Working with a glossary or list of terms is essential to ensure consistent translations. Sometimes, I am asked to use certain glossaries, but most of the time I am allowed to choose freely the terms I use for IT projects.
In these cases, I try to employ words and expression that are commonly used in the IT World. The Microsoft language portal is a nice resource for that. I don’t use it uniquely for the translation of Windows-related strings, but also to know how certain terms are translated in general. If you don’t have any specific terminology to follow, it’s always nice to stick to the terms of the OS most people use.
Apple doesn’t have such a website unfortunately. They do however have a very well done support website, where you can switch from a language to another quickly and easily. It’s a less direct, more time consuming way to search for terms, but it helps a lot when translating software for Mac.