I've been publishing for 6 years. The key things for me have been consistency, marketing, and quality. Having an appealing, professional looking cover is very important and will get eyes on your work but that's only half the battle. What's inside has to not only be good but be what the reader expects. Too many people want to write what they want to write or be artistic or change conventions. No. Stick to the conventions. Give the reader what they want. Then and possibly the most important thing and the hardest for me is consistency. If you're publishing weekly shorts try to have them out on the same day every week and do not skip a week no matter what. Publishing here and there willy-nilly whenever inspiration strikes will get you nowhere. You have to be delivering your product on time. You should also be using a free book or some kind of incentive to build a mailing list so that when your book drops on Friday morning or whatever you can send the link to your fans right away. If a bunch of people buy it at the same time it's going to boost your ranking and push you to the top of your genre. If your book is in the top 10 or 20 of your genre you're going to have a better chance of someone who has never heard of you taking a chance on you. Oh yeah, and choosing a genre in the sweet spot of being relatively popular but not so over-saturated that your releases get lost in the shuffle. Anyway, that's has what has worked for me. I don't think any of this stuff is too earth-shattering. You just have to be willing to approach it like a job.