Well from previous people who have purchased from me they like to know what makes your designs unique and different from anyone else, also the best thing you could do at this time is to build rep on thetechgame because know one will buy from someone who has just joined because they don't know if they can trust you or what type of attitude you have towards people, maybe show a portfolio of your work & maybe help out the community buy making a Graphics shop to help build up your portfolio and so people can get to know you as a person.

sellfy
graphics river
deviant art
behance?
the tech game

I make my money mostly from Twitter. The "problem" with twitter is that its not so much of a store as it is one-to-one client work. So you would have packs and resources on sellfy but specific headers and things like that through twitter. It can get work intensive. Biggest thing is to just not overwhelm yourself and you will be fine

Thanks for all the help.. I will try your suggestions.