Hi
Many Rootschatters start off with Familysearch, which give good results in many cases.
You will generally need to know "as much as possible", but the actual Parish (Sw: Forsamling) is essential.
Then you will need access to one of the three record providers (Arkivdigital, SVAR, genline)
And, when the parish is known, it is realtively easy in most cases to look up in the birth & baptism book....
(Swedish records are nice and neat, probably the best in the world, but of course you will need to have a reasonable grip of the lingo...)
Good Luck!
Jan in Norway