This is a great question and one I faced in my own business of branding. Our contract has had a few different iterations as we've scaled, but we always consulted with legal experts who specialize in our business.
With that said, I would not recommend writing a T&C entirely by yourself for a few reasons:
1. You run the chance of putting yourself or your contractual partner at risk by using language that isn't legal.
2. Even though you may be well-versed in your particular business, or you examine T&C's from your competitors, it won't be tailored specifically to your business and needs.
3. If a situation that should arise where the contract is challenged, and it is not legally sound, it could be financially and emotionally expensive.
What I would recommend:
1. If you have some trusted friends in your same field, sometimes they are willing to share some bullet points on what to include/what not to include, which can be very helpful.
2. Make a working draft/outline of what you'll most likely need to cover in your T&C's.
3. Seek out a business attorney who specializes with businesses like yours, preferably who have expertise in the start up world. You'll find their rates are often more reasonable.
4. Share the working draft document, express certain situations applicable to your business operations and have an attorney guide you on how to protect both you and your customer, given that criteria.
As a branding firm, we work with all types of clients who are concerned with copyright law, privacy, etc. There's no quick, cheap way around it. You can certainly streamline the process as I've outlined above, but you want the best for your business and you want to protect it properly.
I'd be happy to discuss or recommend some partners we've used along the way, depending on your particular situation. I'd be happy to share some insight to you for free.