When it comes to synonyms for the phrase "start doing," there are plenty of options that can be used to express the same idea in a slightly different way. Some possible alternatives include "begin," "commence," "initiate," "embark on," "launch," and "set in motion." These words all convey the sense of taking action or starting a process, and can be useful for adding variety to your writing or speech. Other possible synonyms might include "undertake," "get underway," "kick off," "take the first step," or "get started." Whatever word you choose, the important thing is to convey the idea of moving forward and beginning a new task or project.