Here's what I do, it works for me, I already have tons of babies.
I take a shallow plastic box, no deeper than 1,5-2 cm filled with moist dirt and simply put it in the ADULT critkets' box. I leave it there for a couple hours, or overnight and then remove it. I don't leave it in there for much longer bc the males start eating the eggs I think, and also as they're laying, they make quite a bit of a mess by moving a lot of dirt out of the little box. It's important that you provide them food while the dirt is in there, in order to try to keep them from eating the eggs.
Then I spray a bit more water on the dirt and close the box. (there need to be a couple holes on the lid, otherwise it starts to molt and there will be no little crickets... ). Later on I check from time to time, if it seems too dry, I spray a bit more.
I don't actually incubate them, I just leave the little boxes at room temps. The higher the temperature the faster they hatch, but it takes usually 2 weeks for them to hatch. Sometimes I put them somewhere the sun gets to them directly and so it's warmer.
When they're close to the hatching date, you need to put the boxes into a bigger one bc they'll get out on the little holes. Also I remove the lids at this time, bc it there are water droplets on the inside of the lid from the heat, the babies get stuck in them and drown.
I usually wait for a week to let all the babies hatch and then reuse the dirt.
If you don't like cleaning up in the crickets' container after the mess they made, you should probably thy what the former commenter said about not using little boxes, but personally I find it easier to get the babies out of the irt this way.
hope I could help, good luck
