Most propagation advice treats every houseplant the same — cut a stem, stick it in water, done. That works for some of these and fails completely on others. Here's what actually works, grouped by technique, with links to the exact steps for each species.
The classic method, and the fastest one: cut a section of stem with at least one node, then root it in water or moist soil. This works well on vining and climbing aroids, but not on rosette-forming plants that don't have a vine to cut.
No stem needed — a single leaf, sometimes with part of its stalk attached, is enough to grow an entirely new plant. The technique differs more than you'd expect between a succulent and an African violet.
Splitting an established root ball into separate sections, each with its own roots and growth point. It's the only method for plants with no vine and no leaf that roots on its own — and sometimes the only method that preserves a variegated pattern.
Don't see your plant yet? The field guide currently covers nine species — browse the full list.