Never forget the bidding.
What if the opponents bid your longest suit?
When should you lead partner's suit and when should you lead your own? Did your partner open the bidding? Did your partner overcall?
Is partner likely to have a better hand having more entries? How good is your suit relative to your holding in partner's suit?
So many factors make us crazy and then I heard "If your partner does not lead your suit get a new bridge partner!"
So let us look at the following hands to help us clarify all these factors.