In the past I try to work with chinese manufacturer.
Some information, I think, you can use :
1. Register as self employed.
2. Research the market for potential competitors and pricing.
3. Register your designs.
4. Understand the fabrics you will be using.
5. Compare prices, quality, printing and communication with the 3 suppliers and choose the one that ticks most/all of your requirements.
6. Request a sample and negotiate a price, to include everything (product, packaging & labelling).
7. When you are happy with the sample, proceed to an order, after agreeing all the details, including payment terms.
8. Ensure you inspect the products before you make any final payment if it's possible by someone in China
9. When you feel you can start to order 300pcs (minimum) per colour/design, then at that point consider China.
Best of luck with your project