Eco earth is the substrate I use when breeding crickets, it works very well. You want it damp but not waterlogged and you don't want it to dry out either. Put a container of it in with the adults for a few days and let them lay eggs in it. You need to keep the eggs warm or they will take forever to hatch and you'll just get frustrated. Incubate the cricket eggs in the upper 80s and they will hatch reasonably fast.
Put them in a plastic container with a couple of very small holes in it for gas exchange and put them somewhere warm. You can make an incubator out of a styrofoam box, heat tape, and a thermostat for probably 50-60$ and it will last a very long time.
80 will take a while.You will be much happier if you can get them to 88F. This is the primary problem with people trying to breed crickets is the eggs and very young need to be warm or the whole process takes forever and starts to become less successful. Once they have gotten past the smaller stages 80F is enough that they will grow OK around that point excess moisture also can be a big problem. If the crickets are in damp conditions, they will very likely develop disease and die. If you can remember this, eggs+very young = warm, 2 week+ = dry conditions with a water source, then you will find breeding crickets is actually very easy.