If you can, try doing some short-term contract work for people who might one day be customers for your products. Often, people call this kind of work "consulting", though consulting really means being asked for advice, which is just one kind of short-term contract work.

The reason contract work is good for entrepreneurs is that it puts them squarely in front of a lot of customers, where the entrepreneur can notice problems or issues that many of them have in common. From that, the seeds of a product idea might germinate, and the company can begin to grow from these early customers.

The down side is that it of course takes a lot of time to do this kind of work, and your market may be running away to one of your competitors in the mean time. So, are there alternatives? For some people, there are. The most usual being to obtain external investment for your business from family and friends. There are downsides to this too, of course. The main one is that if your business isn't as good as you initially thought, you might disappoint these family and friends, which feels really bad. Plus, you probably learned something during the failure, and perhaps are ready to try again. Good luck getting money from family and friends for another business, if you screwed up the first one.

So its a balancing act. Lose speed but gain experience. Or gain speed but forego early customer interactions. These are not the only two possible outcomes, but they are representative.