To be successful in business you need both marketing skills and finance skills. One is not a substitute for the other; you need to master both.
Marketing is simple. It's about creating and retaining customers at a profit. It is as simple or as complicated as that. Most people can only do one or the other. They can create customers and not make a profit or they can retain them but lose money over time. It's a complex thing.
Marketing is the most powerful lever you can pull in business. Use marketing wisely, judiciously and commercially.
Marketing is the predominant philosophy of business: you make money by delivering to consumers what consumers want. No matter what size or scale you are, you need to understand what the consumer wants to buy from you. NOTE: That is not always what you want to sell them.
So how can you develop a smart marketing strategy? Check out your competitors. You want to create a proposition that is as unique as you can make it. Remember, very few businesses are completely unique. If you are, genius. You'll be exceptionally successful very quickly. Or a pauper. For everyone else: put together a cocktail of things that consumers want to buy.
Once you have your cocktail, work out the benefits of your business. What do you want consumer to know about that will make them buy from you? Create awareness of those benefits. A key way of doing this is to encourage trial of your product. You have absolutely got to get people to try it. Sounds blatantly obvious but it's sometimes the hardest thing to do and it can cost quite a lot of money.
The last pillar of marketing is to increase the usage of your product. Get people to buy more often and increase basket value.
The measure of a successful business, in my mind, is how sustainable the price premium you are charging is. Any idiot can reduce prices to sell things. Marketing is about sustaining the best possible price over a significant period of time.
Always remember this: The cheapest money in the world is your own. If you can generate money and keep it in the business and use it to build your business, it'll be the cheapest form of funding you can get. As soon as you bring in external funding, at least half of that person's objective becomes 'getting a return'.