Although English is considered a universal language, many readers of technical documents will be non-native speakers. To accommodate all readers, remove ambiguity, refrain from the use of idioms and subjective writing is a must. Technical writing should be explicitly clear.
Readers of technical documents may or may not have technical experience. It is important to not assume the reader has a high level of technical knowledge. Write with enough detail that, regardless of the readers experience level, all should be able to conceptually understand what is being written.
While writing, keep in mind that some readers may be using Google Translate. The use of fancy obscure terms, abbreviations, and acronyms may not translate well. When using abbreviations or acronyms, be sure to have it spelled out previously in the document or include an abbreviation list at the beginning of the document.
Lastly, the addition of visuals to your writing will assist the reader in following along with what you are describing. Adding captions to the visuals maintains clarity and further assists the reader in understanding and applying what has been written.