Propagate some cuttings indoors over winter, and you’ll have loads of coleus come springtime.
That’s exactly my plan! Just pop the stems in water, and you’ll see roots sprouting in a few days.
Yes, that’s the idea! Once roots form, you can plant them in pots indoors. When spring rolls around, transplant them outside. Just make sure to keep learning and adjusting as you go—you’re on the right track! 
That’s the gist! Use quality potting soil, and in a couple of months, you’ll likely be able to take new cuttings from the ones you’ve propagated. 
Might need to chop and propagate a 2nd time. Otherwise you could end up with a 4ft bush.
Skip the middleman and plant it straight into the soil.
I’ve had success with some coleus varieties, others not so much.
Watch out for pests like mealybugs—they can hitch a ride indoors with your clones. I spray my outdoor plants with a mix of 2 tablespoons of Dr. Bronner’s liquid castile soap per liter/quart of water every 5 days before bringing them in for winter. Any commercial insecticidal soap works too.