At home try to wear them around for 30 minutes 3 - 5 days before you go skiing...this will let your foot get used to them, walk around - do not sit down in them.
If something is bothering you, come back into the store for some tweaking
Go skiing
After skiing
Clean your boots with a dry brush or soft cloth
Remove your liners from the shell, let them dry out completely
Light buckle up your boots, check the tongue is in the correct position and not crooked
Store them away from extreme temps