Hi Sharon:
There is an abundance of information on the Web that has been published by university Extension specialists and state / federal agency professionals.
Here is a link to an excellent guide assembled by the US Forest Service:
https://www.na.fs.fed.us/spfo/pubs/howtos/ht_prune/htprune-rev-2012-screen.pdf
Due to oak wilt concerns, prune only from late October to early March.
Best, Jay