Here is what I a told ....
Crickets are pretty easy to breed, just feed them fish food, cat/dog biscuits etc and the main thing is to always have something for moisture otherwise they dehydrate and die off prett quick, some people use a dish filled with water with a sponge/gravel init so they can drink but not fall in or they will drown or you can just use lettuce or grass but you must make sure they have fresh grass/lettuce each day so it/they dont dry out. Im using grass at the moment and seems to be ok but they could be getting moisture from the vermiculite as thats alway moved around.
once theyre older enough to breed (once the males start cherping) just add a dish with moist sand/vermiculite for them to lay eggs in and replace every couple of days and keep it covered in a warm place and they'l start to hatch in 1-2weeks. with sand ive found it dries out pretty quick so im now using vermiculite and that seems to work much better (you can get that at a hydroponics shop/ sometimes a garden centre/trademe) Ive also herd of people using pumice or a mix of pumice and vermiculite
Temperature wise I had mine just sitting ontop of a tropical fish tank and they were about 25 C and bred ok but now I have them in a wooden box with a 40watt light bulb init and temps around 30-32 they grow alot quicker and seem to be breeding flat out but still waiting on my first batch to hatch out from this lot in the coming week or so!
Sorry im not to good at explaining things I hope the above makes sense, if you have any further questions fire away.