How easy/hard is it to propagate a cactus or another succulent from the cuttings of a leave or similar, and what is the best way to go about this. I've read of root balm or something but have never seen it.
usually you just take your cutting then let it air dry for a few days then put it in a gritty soil mix to root
Many succulents wil grow very easily from leaves. Just break one off and lay it on the surface of the soil, and it will soon sprout. Some people poke the end into the soil a little.
With succulents and cacti, the soil should be just damp, not wet or they will rot.
I have never used any rooting hormone on cacti or succulents.
I've tried sinking it in the soil a lil bit and it just ended up rotting but if I lay it on surface it should root soon? Should I keep it humid or just mist the top of the soil
Just break a leaf or a piece of the cactus off and leave it lay out for a couple of days. The fresh cut end needs to dry, or it will rot when you plant it. The cactus will not likely wither, or show any ill effect from this.
Dampen some sandy soil mix. You can lay the pieces on the soil, or plant them upright. Just do it very shallowly. Do NOT plant them deeply.
You can use some wooden skewers like you get in the kitchen dept at WalMart ($1.00 a pack) to support the cactus until it roots if you want. These skewers are good for a lot of things, so I always try to keep them around.
Honestly, if you just break off a piece of cactus and throw it on the ground here, it roots. I wouldn't water it at all, don't mist it. It doesn't like a lot of water. Doesn't like to die of thirst tho, either, but it isn't likely to do that. Just use some common sense.
What kind of cactus are you trying to root anyway?