First, create a fixed walkthrough formed with N maps. You must try it manually first.
When this works, you can define a serie of parameters that you could vary. The RNG output should be used for calculating these parameters. Begin using manual values for this. Same input should generate the same output map, in order to re-create the previous maps retrieving older values.
Keep in mind that the randomness must be consistent, in order to not make your game unplayable.
Remember that "A good randomness began with a good manual design"