"Success" is just a word. It means different things to different people at different times. Plus it's seen as an external factor when it should be part of you.
Success is internal. Ironically, any decent success book will tell you this but it's conveniently ignored by most of us. It's a feeling of things being accomplished on an on-going basis, not just a one-off like winning the lottery. Together with that there's a sense of increasing confidence in that skills and knowledge have been learned which means you can do a better job and make better decisions as you go on.
See what's significant. You can shift the emphasis from success only being how much money made that month to whether you've chosen to take actions relevant to building a long-term business. In the short term, somethimes these two things don't necessarily go together. It's a question of building right and getting the pay off later on. Of course, the more success you have in this sense, the more the two increasingly run together.
Know your own self talk. It might be a cliche but self-knowledge of your own thinking processes can save you a lot of trouble. You can become conscious of when you're starting to sabotage yourself or when you're trying to ignore that you don't know enough in order to get something done or when you're oversimplifying and being too optimistic about a situation.
Trust yourself. However, do take action as this builds confidence and the obvious ability to get things done. You need to trust yourself in order to have that on-going feeling of success, that feeling that you can do things. This means forgetting about what you might have thought were any constraining rules as to how you can take action and what you can do. These "rules" are mostly in your head. As long as you're not breaking the law or hurting anyone, of course, you have freedom to be creative in your enterprise.