I don't know numbers very well, so I couldn't tell you exactly how many to start with, I just sort of wing it. To get larger, efficient colonies it is best to use a rotation system for both.
<U>Mealworms</u>
Have several containers (lidless or screened top works best, since moldy substrate forms easily in humidity and has to be tosses along with precious eggs) setup with substrate (the more varied you make it the more nutritious it will be). Place a bunch of beetles in a container for a couple weeks, then move them to the next container and leave them there to do their business and so forth. By doing this you allow them to lay max eggs. Replace beetles as needed and use as many containers as you feel works best.
<U>Superworms</U>
Pretty much same concept as mealies, except they seem to do much better when they have hiding spots and places to lay their eggs, such as layers of bark in each container.
Remember that worms of both species will eat the beetles! Good luck