Sorry this may have been very important at the beginning but..
Usually people kind of lean in a bit and kiss both cheeks starting with the left one. That’s the one I always go for unless it’s the huge hug for people like Morby and Clara who I know better.
Guys do that but usually only with women. Otherwise they just do the handshake or a slap on the back if they’re really close friends. For example my host father does that with my host sister’s boyfriend a lot. If women don’t want to greet men with a kiss then they extend their hands out first to just shake hands.
[this is the only picture I found no idea what's going on it looks like Rio carnaval or something, but anyway they're finishing up the double kiss-start on the left!]
This website has a good short summary of important information but yeah do research on this sort of thing before arriving: