Tip#1: If you take the metro to go there, buy a sp...

Tip#1: If you take the metro to go there, buy a specific ticket to Versailles and only use this ticket. Don't use your intra Paris ticket under 2euros
Tip#2: Come during the Water show garden show. It definitely worth it, and give a full experience of Versailles
Tip#3: in weekdays, I'd arrive there around 12pm, there is plenty of time to visit all Versailles
Tip#4: you should start with the garden to avoid the crazy morning line on the left that last about 1h and half. The garden do not have line at all. Come back to see the palace around 3pm with literally no line!
Tip#5: Online ticcket do not allow you to cut the crazy line for the palace. But it will save you some precious minutes. Just get it!