You can make life a little easier for yourself if you go out and get some Rapid Rooters, or Sun Leaves plugs. They are made from a spongy material which is actually composted tree bark, and I am pretty sure both brands are micro-biologically active (I know Rapid Rooters are). These are perfect for clones but other things will also work, such as rockwool cubes, coco coir, or a soil-less mix.
I can't delve too far into why being biologically active (with beneficial micro-organisms) makes a medium like Rapid Rooters so appealing, and aside from it holding a more perfect air-water ratio. At the very least the presence of beneficial microbes makes it much more difficult for any of the nasty fungal infections from being able to colonize the medium and affect the plant. Sterile mediums are all good in theory, but in practice they just don't stay 'sterile' for very long with mold spores being ubiquitous and awaiting conditions of high temps and humidity.
Clones need to be in an environment with high humidity, at least for the first several days. Obviously this is where the dome comes in. They will root faster when temperatures within the medium are mid 70's, which is why a seedling mat or similar suitable heating pad could help.
A good cutting is at least four inches and has at least a couple sets of healthy leaves. You need to cut the stem (with a sterile blade) again at a 45 degree angle, in other words cut it at a \ slant \, to expose more surface area of the inner tissues to the rooting hormone. Surround the fresh cut, and the rest of the lower portion of the stem there with the rooting hormone. Cover as much as is going to be stuck into the medium, then stick it into your medium.
Keep saturated. If you're using Rapid Rooters or similar inner-tray-with-drain-hole style repository you might consider putting a thin layer of perlite at the bottom of the tray, then placing the inner tray as usual on top of the perlite. This will allow the medium and growing roots to absorb/seek moisture without them sitting in stagnant water.
Whatever you do, keep the dome on completely for the first three or four days. Put it under HO-fluorescent or CFL's. Condensation is going to build up on the inside of the dome, and it's a good idea to simply wipe this away (dry) a couple times a day. If the leaves themselves are continuously drenched in water (like those droplets on the side of the dome), those leaves might begin to die and rot. You want things humid, but not utterly and constantly soaked. After a few days you can open the vents on the dome if it has them, or leave it partially ajar.
Root formation should be obvious after a week to ten days, then you'll transplant them into their vegetative homes.
Here are some other considerations that are more personal preferences of mine. I keep my rooting clones healthy by providing them with a few supplements:
Maxicrop Liquid Seaweed - Plant growth hormones/regulators (cytokines, gibberellins, auxins) which plants under stress are lacking. Good source of potassium and trace minerals.
Botanicare Liquid Karma - Also derived from sea kelp with addition of humic acid, yucca extract. I alternate between using LK or just Maxicrop.
Botanicare Pure Blend Pro Bloom - I only use this stuff for clones and foliar feeding. Bloom fertilizers like this at 1/4 - 1/8 strength are good for clones as phosphorous is particularly necessary for root formation. I like PBP for this purpose because it has some nitrogen, and should be pretty complete in terms of secondary/trace nutrients.
Superthrive - for sickly or less vigorous cloning endeavors. Auxins and vitmains including b-complex, but highly concentrated and synthetic. Superthrive really shouldn't be necessary when cloning healthy, vigorous plants.
