How to greet my boyfriends parents for the first time ?

[RPattzlover]

How should I act around them too ? I want to give them a good first impression of myself, and i want them to like me. Should I give both parents handshakes/kisses on the cheeks ? Of course i should use my manners, e.g. please, thank you, etc..

and what if they say "treat our home as if it were your own" (or something like that), i should go rummaging through everything, right ?

thanks in advance
oops !! i meant i SHOULDNT go rummaging...