Can it be written entirely by myself (never got legal training) following the examples of my competitors? If not, is it worth writing it myself and then asking a lawyer to review? Thanks!
Your first point of reference should be experience.
The most effective way to create your ToS is to consult with a lawyer who specializes in your industry. This also hold true for your that and any business legal document.
It’s true that you can find different online services and templates to assist you, but the truth is that these documents could very well be null and void.
Your business is specific and unique and your ToS should be the same way. I advise against copying your ToS or using one of the “easy to use” sites as they will almost certainly fail to include or capture everything. Read more: https://lawtrades.com/blog/protect-website-liability/
In my opinion, copying your competitors legal documents will not work for you in the long run. The odds are high that the business had their documents customized, and by copying and pasting you are claiming that your business has the same features and services which is highly unlikely.
Hope this helped address some of your concerns. When you're ready, you make your request completely free at www.lawtrades.com to get a better feel for the process.
Feel free to mention "clarity" for a discount :)