Nick here from Shopify.
If you have multiple products with the same design, your best bet is to set up the product with variants. Shopify has a guide going through everything you need to know about variants here. Something to note is you mentioned about male and female t-shirts. I would personally make a distinction like that a separate product and have the variants more for size, color, material, etc. You can also see the YouTube video tutorial about adding variants to your products below:
Printful also has a guide on product variants which might also be of some use to you. You can see it here.
Hope this helps!
All the best, Nick
|2 hours ago|