Aero's work great, but if you have a clog or a fuse blows your in trouble. I find the root riots using a heated propagator produces roots just as fast if not faster AND the heated prop/root riots are second to none for sprouting seeds-no germination-right into cube, right into propagator-sprouts in less then 5 days. My aero has been collecting dust for awhile. The whole set up with a tray, root riots, clonex, 2" dome(for seeds), 7" dome(for clones), and heat mat costs less then 50 bucks, cheaper then many DIY cloning machines I see as well.
Nice little setup for seeds and clones! I would never grow without a heated prop and root riots(or rapid rooters/similar product). And if the power goes out it's not a big deal if the heat mat goes off, it just shaves days off of sprout/root time.
So many different ways/methods people swear by. I will say *heat* is what brought my success rate to near 100% with seeds and clones, before I used the heat mat 75-80% was good for me. People have success cloning right into soil, so there is many ways it can be done.
I also find that making a cut with a razor blade NOT scissors(they crush the stem when you make a cut, but hey, I get lazy some times and scissors def. still work), shaving off the outter layer of stem up about a 1/2", and making your 45degree cut right through a node all make a big difference no matter what technique you use.