I'm somewhat new to gardening, but I have had pretty good luck over the last year or two saving seeds from veggies I buy at the store and then planting. Peppers (bell and hot), cantaloupe, pumpkin, etc. I went to a class about saving seeds and that worked out, though I've found that saving tomato seeds is even harder than people say it is.

I've planted some berries in the hopes of having some perennial fruit, and they are doing really well this spring!

It's too late to plant spring wheat, but I will be planning ahead for September-ish and getting a winter wheat "crop" in.

I am thinking that this weekend I will try to plant some sweet corn - perhaps a single seed packet if I can still find one at a garden shop.

My approach has been to try something, learn, get better. That's the best advice I can give.

Depends on your goals. If you are just looking for calories, you probably can't beat potatoes. You can grow 100lbs of potatoes in a 4ft x 4ft plot. Maybe even more than that.

If you're looking at maximizing nutritional value, sweet potatoes might be a good bet. You eat the leaves and the tubers. Similarly to potatoes, you can grow a large quantity in a small area.

If you're looking for luxury items that may be hard to find in a shortage, then you have a lot of options. Though they might take more or less skill depending on the crop and climate. (Like artichokes).

Contact your local County Extension office. They should have useful info specific to your location.

https://pickyourown.org/countyextensionagentoffices.htm

There was this concept of "victory gardens" in the past

if you're starting a garden,I highly recommend a tomato plant. store bought tomatoes are incredibly bland in comparison.

And seek out heirloom varieties. They might be ugly but the taste is beyond compare.

Fruit trees are often prolific.