Late winter is the best time to give your Japanese Maple a little love. Remove with sharp pruners, any dead, damaged, crossing or rubbing branches. If you're not sure if a branch is dead or alive, scratch bark with fingernail. You will see green wood underneath if it is aive, and brown and brittle if it is dead. Prune back to next branch or rigth above leaf nodes (swelling at this time).
While your examining each branch, check for scale and pick them off and dispose. Any suckers from base can also be removed cutting as close as you can to the main trunk. If your maple needs a little shape, do so now. The tree still has time to set new nodes and flush nicely this spring.