Beans are one of the easiest of vegetables to grow, and one of the first that I ever saved seeds from. One of the first things to think about is whether the variety you're growing is a bush or pole bean… bush varieties grow into knee high plants and tend to bear all their pods at once, whereas pole varieties need poles or netting and can climb to 8 feet or more while producing gradually for months. The other two categories to consider are dry beans vs. snap beans… snaps are eaten fresh while dry beans are allowed to fully mature into protein rich beans. All these different types are the still the same species though, Phaseolus vulgaris is a broad species!
I always direct sow beans, beginning in late May here in Nova Scotia, but they can be planted as late as July 1st for early maturing bush varieties. I like planting in rows, with bush bean seeds spaced 3-4 inches apart in the row, and pole bean seeds a bit further apart at 5-6 inches. They do best in fertile soil (most veggies do!) but as nitrogen fixing legumes they can tolerate poorer soil than other crops. I tend to plant them in our less than perfectly amended areas of the garden. They like full or partial sun, and can tolerate short periods of drought without much harm.
By early/mid summer bush beans will be just about fully bushed out and flowering. Simply keep them weeded and they should take care of themselves! Pole beans will begin sending out runners after 3-4 weeks, they twine in all directions reaching for something to climb. Once they find support they'll explode into growth, climbing as tall as they can and then filling out into a jungle of foliage. For supports I like to use either wood or bamboo poles tied as tipis for extra stability, or mesh netting attached to sturdy posts. Think strong when building for pole beans, they can be surprisingly heavy when fully grown and laden with pods.
For fun one year I cut an extra tall 15 foot stake from the forest and added it to a bean tipi. The Purple Peacock beans climbed all the way to the top, and then tumbled down the other side. We had to knock the whole thing down to harvest them, and stretched out at the end of the season the vines were about 20 feet! They'll adapt to whatever size of support they have though, even just 4 or 5 feet high will still be fine.
Beans are self-pollinators, meaning pollination happens within each flower and within each individual plant. It makes life easy for seed savers because we don't need to worry too much about crosses between varieties, they're perfectly happy inbreeding. I tend to isolate my beans rather minimally, usually just separating two different bean rows with a row of something else. Beans will sometimes cross pollinate, but I've never seen more than about one percent of seeds turning out crossed. The trick is in "rouging out" and not saving seed from the off type plants, something we can do on a small scale but wouldn't be practical without greater isolation on a field scale.
Keep in mind it's those off types where new varieties are born! Each cross is the beginning of a whole new strain, slightly different than anything ever grown before. If you're lucky enough to find a cool new off-type try growing it out… simply save seed from plants that carry the traits you want and within a few years you might have a stable new variety! That's more of less how the countless thousands of bean varieties in the world came to exist. Seeds are a very fluid thing, it's possible to not just preserve existing diversity but to expand diversity!
As for collecting and processing bean seeds, the seed is the bean itself, so if you're growing dry beans for food just set some aside for replanting. Snap bean pods too will dry down like dry beans, just leave them on the plant past the fresh eating stage ideally until the seeds rattle inside the pods. Often in our rainy climate we can't get perfectly dry pods outdoors without pods going mouldy or seeds sprouting still in the pod, so what I often do is I cut or pull the entire plant and hang them up indoors. As long as the pod is still attached to the vine it will continue to mature it's seed, all the energy left in the cut vines will be sent to the pods. Just so long as the beans are fully formed before pulling they can dry down and mature quite nicely in the barn rafters.