Feed the worms at least once per week, this is plenty of time for them to have consumed most of the last feed and i find they start to disperse into other areas of the bed.
Aerate the bed at least once per month. i do this with a fabulous tool that is designed for turning compost heaps. It looks like a giant cork screw. I just screw it deep into the bed, it goes straight to the bottom then pull. It literally pulls out a plug of bedding, worms and all, give a little tap and it all falls off. Aerate the bed to add oxygen and to bring up unprocessed bedding from the bottom. It also prevents the castings from becoming too compacted and this also allows the worms to move around easily. I do this just before i feed so as to not send uneaten food to the bottom of the bed.
Maintain moisture, I learnt this the hard way. I let the bed dry out through hot weather and lost the lot once. I find most of the moisture comes the food i feed, i always feed wet sloppy food. I keep the bed just damp not too wet not to dry. Sometimes if i feel its drying out a bit i will add water. My system is free draining so even to turn the hose it would do no harm. To help maintain moisture i keep the entire bed covered with wet hessian bags, this also encourages the worms to come right to the top to feed just under the hessian. The hessian bags are then covered with black weed mat (the breathable kind) and this keeps the bags from drying out too quickly. I re wet the bags every time i feed. I will generally keep the entire bed covered with tarp to keep the rain out (not that we have had much of that lately) but i would not allow it become saturated with rain. I have heard of worms going walk about during rain storms. This is because as the ground becomes saturated, the tiny air pockets in the soil fill with water and since the worms breath through their skin they can suffocate unless they come to the surface.
Maintain temperature. Now this is one i don't really have much control over. My worm beds are outdoors under a giant Poinciana tree. Its mid winter here in Rockhampton which is located right on the Tropic of Capricorn. The temps range from around 5degC/40degF early in the mornings to a beautiful top of 25degC/78degF during the day. This is ideal for worms. Summer on the other hand is not so worm friendly. Its not uncommon to have 3 weeks straight of 38degC/100degF with the nights rearly dipping below 20degC/70degF. The only thing you do in this extreme is to ensure the worms have enough depth in the bed to bury themselves to a level that is cooler, it needs to be at least 30-40cm/12-15inches deep. A small bed is going to heat up quicker than a large one. Even the dog will dig a hole to lay in to keep cool.
I cant really advise on those that have the opposite to deal with although i have seen photos of an insulated outdoor worm bed covered in snow with active worms inside and a thermometer showing 20degC. You could also use compost that is in it's heating stage to help warm the bed.
Maintain these four elements to have your worms flourish and multiply.