Failed many times with Reddit ads. Reddit is not for marketers?

I know Reddit is a gigantic forum which has millions of people surfing through everyday. So I think it has so much potential for me to make some money off it. But I still don't know how to control this beast

I tried a several campaigns. Advertise tshirts. Targeting right subreddits, US audience. I've got so many clicks but 0 sale so far

What I did was uploading the image which has a model wearing the shirt and put the link on URL field.

I know I did wrong but I can't even find any documents/tutorials about Reddit ads.

Should I change my products to advertise?

Someone got success with Reddit ads please give me some advices

Thank you