I am looking to setup a t-shirts and caps designing site. What software should I be looking for?

If you’re trying to setup a site that does something shouldn’t you develop the part that does the one thing your site is supposed to do?

Or do you mean what software should you use to design the site itself? Because in that case you should not rely on a program if you’re trying to do something that is not standard. Design softwares are generally pretty bad at doing anything that has not been done and standardised before.

For your website, if you don’t have development experience or money to pay for someone, I generally recommend Shopify. It’s easy to get started and really good out of the box.

If you have some time and want more control, Magento can do just about anything you’ve ever seen in a store. You just have to either build it yourself or hire someone to.

If you’re just starting out, I’d go with the first option and worry about the dozens of other things that come with starting a business. Shopify is about as easy as it gets while still looking professional and fairly complete.