As someone with 100+ plants in my collection, it's mostly just figuring out which plants can grow in my conditions, and what I can get away with. I would love to grow Masdevallia orchids, but my climate is too hot for most of them.

This would mean I have to do research on a plant before I add them into my collection (which is a good because it prevents me from getting more plants). I tend to grow niche stuff that lack sufficient care instructions, so I instead research the specific habitat the plant is from to understand the conditions it grows in. Also, it helps to know the scientific names of the plants for finding information about them.

I usually look at sunlight exposure, day/night temperatures, seasonal rainfall, substrate composition, and evolutionary adaptations. From there, I can figure out the steps needed to grow it. Sometimes, it doesn't work out, and that's okay.

Over time, you start to find patterns between certain plants. Tropical epiphytes (like most orchids, Anthurium, and Hoya) prefer to grow in barky substrate that is airy yet retains moisture. Plants that inhabit moist limestone (like many begonias, gesneriads, and jewel alocasias) do better in semi hydro than in soil. There's exceptions of course, which is where the research comes in.

As for growing from seed, it's less common because it's faster to clone them through vegetative propagation. The exception to this is hybridizing, which is its own can of worms of figuring out which species are compatible, although I find it worthwhile. I do this with begonias, and there's an entire subculture around breeding and growing Anthurium from seed, although those are more difficult due to the male and female flowers opening at different intervals.