Is that all I need to start my business, and I already have a heat press machine..
you need: - vinly cutter(cameo is good, but whatever you chose needs to have contour cutting)
- heat press
- material - vinyl( you can go one color so you have less expenses with vinyl for starters)
- t-shirts(let's say 100 pieces, and you need to have few sizes)
- 100 envelopes for sending to customers
- little tool for scraping vinyl(not necessary if you got girlfriend with nails

, but very help full)
- 100 plastic bags to put those t-shirts inside
- maybe, your choice 100 nice boxes to brand yourself
here is example:
https://3rdrailclothing.co.uk/package-like-a-pro-with-t-shirt-boxes/
- online starting point to promote your business: facebook,instagram and so on
- web page when you are ready: the cheapest(the fastest) solution is 30 dollars per month
- domain and hosting for that site
- printer (lets be serious, you don't wanna hand write addresses of your customer...)
-a lot of determination
Did I forget something guys? -.-
edit: I think you need paper for layer between heat press and vinyl, but I am not sure, cause I don't do vinyl

And silicon pillows maybe? The vinyl masters of this forum will tell you
