Dont bite off more than you can chew.

贪多嚼不烂。别不自量力。

Don't bite off more than you can chew.

不要去咬你嚼不动的东西。

Don’t bite off more than you can chew and say something like: Start &Finish Project A.

不要试图一次性把一项大任务做完，例如，开始并完成项目A。

However, remember that your current position and duties are the most important, so be sure not to bite off more than you can chew.

不过，切记，你当前的工作和职责是重中之重，所以量力而行，不要贪多。