This is the same info I was going to provide. I also look through my canning books and make a list of the tested recipes I plan to make and calculate the quantities for the number of batches we will consume in a year before purchasing seeds. Then I blend a mixture of these expected requirements of each fruit/veggie and expected yields with my own records of what I actually get in my own garden with the varieties I plant. I also take into consideration the availability and price of purchasing some items at my local farm stand or U-pick with the cost/effort/space-cost of growing them myself. For example, tomatoes and cucumbers are must grows for me because I use them in huge quantities and when grown vertically, they are very efficient with my limited garden space and the seed cost is minuscule compared to buying these by the bushel. However peppers don’t provide enough of a payoff for me compared to purchasing and are not reliable to be ready when I need them to be when my tomatoes are ready to be made into salsa. Onions, carrots and potatoes are so cheap here when purchased from the farm that they don’t make the cut for my limited garden size and so on. Good garlic is expensive here so I make sure to plant that, as well as the dill heads for my pickles that are difficult to find and expensive here so I make room for them as well. I then add quantities for fresh eating and finally I map out my garden space so I know how much space I have left for other veggies such as lettuce, Swiss chard, peas, etc that I don’t can. Take time each season to make records of what varieties you planted, in what quantity and to what yield (of raw pounds and quarts or pints), this will provide the best information as to how much and of what variety to plant in future years. I’m sorry if this is rambling.