Stem cuttings are pretty easy and almost always successful for me. I usually use shoots that are 4-6inches long. Here is an example, Below is a plant that I have in the greenhouse currently.
You can see that it has a lot of shoots coming off the main stem and up from the stolons.
Here is looking down into the pot, shoots coming up from the soil or the base of the plant are the best to use for cuttings
Here I have two potential cuttings, the one on the left was coming up from the soil I would just plant it as is. The other is from higher in the plant and I would trim it before using it as a cutting.
Here is the same two cuttings after the one on the right was trimmed. Notice how I took off most of the leaves to reduce water stress on the new cutting, and trimmed the bottom so that there is a node near the bottom. I would plant these as is (you could use rooting hormone on the cutting on the right, but it isn’t necessary). Plant them deep in moist soil so that only the top 2ish inches are above the soil.