A proper fit with ski poles is essential for optimal posture and balance.  Let's tackle the basic questions:

Q: What size of ski poles do I need?
A:  To find the correct size of poles, you'll most likely need an assistant to aide in measuring.  Hang your arm down with your elbow against your waist.  Bend the elbow at 90 degrees so that your forearm is parallel to the floor.  Have your assistant measure the distance from your thumb in a clenched fist to the floor.  This length, in inches, determines your standard ski pole length.  Remember that ski poles sink into the snow about 2-3 inches when pushed. 

Q: What if I don't have a helper?
A:  No problem!  Just grab the closest broom handle and hold it bristle-side up..  Mark where your thumb is and then measure it.

Q: What if that all sounds like too much work?
A: No problem!  If you find yourself to be a generic body shape, then feel free to use this generic sizing conversion - remember, this is generic stuff.:

   Height    =  Pole length
  ------------------------
   6'7" or +   = 56"
   6'4" - 6'6" = 54"
   6'1" - 6'3" = 52"
   5'10" - 6'0" = 50"
   5'7" - 5'9" = 48"
   5'4" - 5'6" = 46"
   5'1" - 5'3" = 44"
   4'9" - 5'0" = 42"
  4'5" - 4'8" = 40"
  4'1" - 4'4" = 38"
  3'9" - 4'0" = 36"
  3'5" - 3'8" = 34

under 3'5" = no poles, they'd just be used to poke out an eye.

Q: What if I'm between two sizes?
A:  It is generally considered best to opt for the slightly longer length.  A pole that is too short causes unnecessary crouching and bending when trying to plant the pole.  This bend is usually too far forward thus altering your center of gravity and may cause loss of balance.   A longer pole is easier to plant directly in line with your posture.

Q:  What is the difference in ski pole baskets?
A:  The basket is designed to eventually stop the pole from sinking too far into the snow.  The determining factor is basket choice is the type of snow.  Deep, soft, powdery snow requires a larger basket which adds surface area to prevent the pole from sinking too far in.  Hard, groomed, or icy terrain requires less surface area, therefore a smaller basket.  The smaller the basket, the less prone it is to breakage and/or snagging while skiing.  Try to find the best size for your average local conditions.

Q:  What is the difference between grips?
A:   Grips are made with a myriad of materials and shapes.  More expensive poles have lighter-weight materials and generally offer a more cushioned feel.  Most have straps to keep the poles closer to your body in a fall, or to just keep them from falling off of the chair lift.