The days between the first day(s) and last day(s) of Passover and Sukkot are called Chol Hamoed literally the mundane days of the holiday (intermediate days). Here are the main laws for these days.
One should wear his holiday clothes if possible.
One should buy his wife and children gifts for the holidays.
Men don’t put on Tefillin on Chol Hamoed.
There’s a mitzvah to go up to Jerusalem and to the Kotel even now without a temple.
Labor or work that is not necessary for the “moed” is forbidden (Some say it’s a rabbinical transgression some opinions say it’s Biblical). If it’s needed for the moed it is permitted.
A labor or work considered something that will cause loss if not done is permitted even if not moed related. For example: public needs, mail, bank services, food stores or when a person may lose his job by not working. The rule is if there will be loss it’s permitted.
Business is prohibited on Chol Hamoed if it’s not moed related. However if there’s a loss involved like if the price will go up or the item will no longer be available you can buy it.
One should not print books on Chol Hamoed.
One should take his haircuts and shave BEFORE the holiday.
Haircuts and saving are prohibited during Chol Hamoed.
One can wash and clean his home.
One can polish his shoes.
One can iron (clothing already washed).
One should not do laundry on Chol Hamoed even for the moed unless he has no other clothing and needs them for the moed.
One can play musical instruments.
Weddings are not performed on Chol Hamoed.
Writing should be avoided unless it’s a need of the moed or might cause loss if you don’t write.