We sold at a farmers' market until COVID-19 put an end to our little enterprise.
I can say that whatever requires the most work -- sells the best. That sounds negative but it also means that a good price can be had.
Vegetables. Think of the most wonderful salad you could put together. Grow those ingredients. You are so very much involved in garden life and represent that. Remember the old adage – in life, timing is everything. Your major competition is the supermarket with its connection to a distribution system reaching thousands of miles distance. Seasonal production will vary across those miles but it will make little difference to their offerings in the produce aisles. THAT is what the customer is accustomed to.
Timing is everything. Keep notes on your own garden production. Realize that days-to-maturity listed in seed catalogs is helpful but isn't likely to reflect your growing conditions very precisely. You want your customer's ingredients to be all there together, perfectly fresh and ready for purchase.
There is this idea in coaching sports that with an ideal team, players on the bench have as much skill as the starters on the field. For a grower that means that a number of varieties is good insurance that your offerings will be fresh and available on marketday. Timing but also having some choices on what may be available for you to offer. It may take only one or two beyond your "standard" but you have added some assurance (insurance

) that your customer will find you there with something they want.
Be patient with yourself, mistakes will be made and growing crops means that they aren't quickly corrected. It's probably best not to do any calculations re income/hours of labor. Vegetables can require some processing so as to get them to market clean and presentable

. Salad vegetables especially may require careful handling and refrigeration. Then, transportation and presentation, everything is fresh and pretty and now, you are supposed to be cheerful and friendly???

Steve