For example, unless you enjoy filing taxes and are well-versed in the tax code, it’s probably a good idea to seek the services of a reputable accountant. Similarly, you should probably get legal assistance in drafting contracts or filing trademarks.
This stuff I've outsourced before. As for actual work handed to me by clients, I've never had the 'guts' to outsource. I'm always afraid the job will be unsatisfactory or it will take more time than if I had just done it on my own.