Depends on what you are planning on actually building, how you plan on flying it and what you have already got. Also depends on how much you wish to spend.

Most planes up to 50cc use one Aileron servo per wing, 1 servo per elevator and one servo for the rudder. (8 channels in total required to have one servo per chanel plus choke and kill - that is a worst case for most planes). In that case, I would use 2 battery packs to power a single receiver and run each servo direct from the receiver - which packs to use is a can of worms and it dpends a lot on the plane, flying style and servos used.

Most planes from 100cc use 2 servos per aileron, 2 per rudder and one each elevator. (11 channels on the scenario above) - Depending on the radio gear, It can be 2 batteries to power 2 receivers (each receiver powering one side of the plane) and the serovs plugged straight in.

IF you don't have a radio that wil cover the amount of channels required, the current options are:

Programmable servos such as the HiTec digitals using "Y" leads from the receiver for matching servos.
Match boxes as mentioned by huck1199
Smart Fly power boards as mentioned by LairdSS - the upper end of the range on those allows programming for each servo.
Futaba S-Bus system

All my planes above 50cc use the SmartFly power boards with Regulated LiPos or A123 batteries. I am just now getting into the S-Bus system but am still learing it as I am a newbie to it.