I'm not sure if you are asking from a purely business perspective or technological perspective, but one relates to the other, so I hope this helps.
1. First and foremost, a reliable, low maintenance phone system. The size of your call center will determine what equipment you'll need, but make sure you buy from a reputable vendor that offers good support, like Avaya or Cisco. My experience is with Avaya and they offer awesome capabilities with very little upkeep.
2. Make sure that your call center agents are well trained. Customer service is paramount to running a good call center. Just think how you want your experience to be when you call a customer support line. Thats what you want your agents to be like.they are taking calls.
3. Make sure with you have a good call accounting computer system to track call information such as: how many calls in a given period, number called from, agent who answered, and length of calls. These are important when tracking trends and types of calls along with managing your call center agents.
Two more things. Have a good telecom person who knows how to troubleshoot the phone system. He or she will save you money in the long run, especially if they can set up call routing for you. Also, get learn about commercial telecommunications including terms used and what equipment you'll need from a telecommunications provider (i.e. T1 or DS3 circuits, etc..)
This is fairly brief, but maybe it will get you started. Good luck in your endeavors.