Swedes use fixed phrases when they gather, or when they write a letter or email.
Phrases to start a conversation vary from very informal ... to formal
Opening phrases
Hej! / hej Ronnie / hej Greta
Hejsan!
Hallå!
Tjena!
To make it even more informal, you can double them too:
Hej,hej!
Tjena, tjena!
PS: Tjena comes from the French "Tiens! as a way to express the fact of being surprised.
They also double it "Tiens tiens ... regarde qui est là !"
During the day
God morgon
God dag
God kväll
God natt
Goodbye
Hej då! ... (let's go, I'am going)
Vi ses! ... (till..;we see each other again)
Vi hörs! ... (till ... we speak a next time)
How do you do.
This is an English phrase that you can't, and never shall, translate, as it is part of a fixed "very British" protocol.
It's not even a question ! So you answer with just the same "How do you do."
So the informal Swedes just skp that part 
But after that you can start asking, things such as
Hur mår du? How are you doing?
Hur är det? How is it?
Hur är läget? what is the situation? (like: what's up? Any news?)
Or even shorter
Läget? Situation? Status?
Formal would be
Hur är det med dig? (“How is it with you?”).
Who are you
Jag heter…
Vad heter du?
Trevligt att träffas!
/ fluent 
/ learning 
/ fan of 
(bs/bl)
