Things that are important to Ice Climbers are familiarity, eventually with enough time you will have a 6th sense to when nana will jump, not jump, and often you will have a good idea of when she will attack by herself, during desynch combos primarily started with grabs since those are ones you will use often you will learn how to impliment random things with nana when your opponent changes in DI.
Also spacing is really important, its the most important thing in the entire game for all characters, make sure you learn the length of your hammers in every single attack and make sure to place it right on the edge of where your opponents character model will be by the time your attack finishes.
DI is important especially for solo popo, learn how to DI for survival since they are pretty light.
Ice climbers also have a lot of interesting tricks for grabs.