A piece of advice to our new Simmers: Have patience. :P
This game will teach you patience, that I am sure of, but you will need patience to go through loading households, loading CAS, etc.
And save your game!! I personally save my game every sim day and if something special has happened. To decrease the change of corrupting your save file; use "save as" instead of "save".
I have a couple of saves of the same households that looks like this:
"Household family name, week3,day1"
"Household family name, week3,day2"
"Household family name, week3,day3"
I generally keep two or three saves of the household to use as a backup just in case the latest one does get corrupted.
