this is hard to help u if u do not tell us more about what u would like to sell …
as for what to sell here lol this is depending on your potential, experience and nature bent to bring something new to the table in one of the existing categories …
I’m a graphic designer. I can design logos, visiting cards, letterheads, stationery, book covers, annual reports, magazines, t-shirts, restaurant menus, flyers, brochures, mockups, etc.
What should I keep in mind while submitting my design?
LOL well if u are so good at all u do not need to ask aything like this to yourself lol just kidding, more seriously, i guess that focusing on quality and originality would thus be the real deal …