I've found by trial and error that temperature and keeping the medium moist are the 2 most important things in getting successful clones.
I had 100% on 3 crops of clones, followed by 0% and two or three tries, even though I hadn't altered the technique, the location or any thing else as far as I could tell.
Then my other half mentioned that the temp in the house had dropped significantly at about the same time as my success ratio crashed. I picked out the surviving cuttings and moved them into the veg room where it stayed above 65F and usually above 70F and my success ratio went back to 100%.
My first attempt, I used Oasis foam blocks, a twin tubed 2' T5 fixture witha homemade reflector about 16" above the blocks and drapped clear heavy plastic over it for a humidity dome, and sprayed them with water 2 or 3 times a day with 100%. The second time my son had borrowed my light and plastic so I repeated it without the light and plastic dome, again with 100%. The third time I quit spraying them and still got 100%. Then the outside temperature cooled off to the point that the AC would keep it around 60 to 65F and I couldn't get one to save my life, but since I moved them into the warm veg room the success returned to 100%.
We live in Eastern Washington State and our average humidity is around 10% to 50% unless it is getting ready to rain or snow. Based on that, in my experience a humidity dome isn't necessary unless you have extremely dry air so long as you keep the medium moist. Nor is spraying really needed. In fact a dome or excessive spraying is a great way to have mold problems. Even with a dome you MUST have air flow around the cuttings or you're asking for trouble.
I haven't seen where the lighting made a lot of difference one way or the other -- except you have to be careful not to cook the clones or dry them out, both of which become more likely with high powered lighting and a lack of air flow. Unless you really provide for air flow through a dome, using a hot light will definitely cook the cuttings.
I have also tried cloning machines, both spray and bubble types and if the water gets below about 65F to preferably 70For even slightly warmer, they just aren't going to root, in my experience, with or without a dome over them.
I have had the same problem with domes that showed up here, they are always to short to root larger clones, so I have pretty much quit using them.
If you want to try this idea a variation that I stumbled on was to use a pair of the deepest cake bottom/cover sets that you can find at your bakery, glue the top on to the bottom of one set, turn it upside down, sit the other bottom right side up on top of the bottom piece of the bottom set that you glued together, after lining the two bottoms up glue them together, then carefully cut the centers out of the two bottom pieces. This gives you a bout and 8" to 10" deep dome depending upon the depth of the covers for under $5.00 US. Then take a hot table knife and melt several slotted holes through the top cover along the sides about 1/2 way top to bottom for air flow. If you are careful, you can easily cut the slots with a sharp knife, but just melting them is easier. JUST DON'T USE THE GOOD SILVERWARE! Actually you can melt the slots with any kind of hot metal object, but it is going to give off some really bad fumes so be prepared for that. Personally I prefer to error on the side of too much air flow because the narrow slots are easy to block off if you get to much air flow.The covers are available in a wide variety of sizes and shapes.
A word of caution is that IF you think you are going to be moving it around with clones inside, then glue a piece of heavy cardboard, thin plywood/particle board to the bottom of your new dome assemble to stiffen it up because if you don't they twist and bend which pops the top of and may even dump your clones out.
Good smoking.