What are the easiest plants or crops for beginners to grow and maintain? 
Beans are fantastic because they grow quickly and produce beautiful flowers, which is an added bonus.
I also enjoy growing herbs like dill and sweet basil. Leafy greens such as bok choy and Kos lettuce are generally easier to grow and can be harvested multiple times.
I completely agree about beans! We planted some black beans by simply tossing them into the soil, and they sprouted without any issues. One year, something chewed on about 25% of the leaves, but it didn’t affect the yield at all.
The only downside is the harvesting process. It takes me a few hours to shuck them out of their pods.
However, their nitrogen-fixing properties make them a valuable addition to crop rotation.
I think I’ll give lettuce a go
Basil is lovely, but it doesn’t thrive in cooler climates. Dill, on the other hand, is great because it reseeds itself. Sunflowers also have this self-reseeding benefit.
I find summer and winter squash to be quite easygoing. Potatoes and carrots are also great options! As for flowers, sunflowers, hollyhocks, calendulas, and most perennial flower bulbs like tulips and daffodils are excellent choices.
How much space is needed for potatoes and carrots?
Both grow well in the space you have. Carrots take a while to germinate and need thinning to produce nice-sized carrots. Planting two or three potatoes, cut into three pieces each, in a whiskey barrel can yield a nice harvest, and they are very easy to grow.
I’d follow Woody’s advice and save space by planting potatoes in a container and stacking them. I use old milk crates with the bottoms cut out and stack them as the plants grow.
For carrots, make sure to thin them out. Otherwise, you’ll end up with a lot of small, twisted carrots.