I don't know if there actually are any rules for how to use "liksom" in swedish, since the word is considered slang and colloquial language. "liksom" is widely used among young speakers, and you can compare it to the english word "like". just like "like", "liksom" has a proper meaning but now most speakers use it in a different context. anyways, this is how "liksom" is supposed to be used:
Annie har brunt hår liksom hennes syster. = Annie has brown hair like her sister.
so I guess in this context it means "like". but the other way of using this word is to just toss it into a sentence pretty much where ever you feel like it. anyways, I could give you a few examples(this is very informal and colloquial language btw):
Jag stod där och alltså det var liksom så jävla mörkt, alltså man såg typ ingenting liksom.
Alltså vi har så jävla mycket läxor just nu, alltså jag kommer liksom inte hinna något annat än att typ plugga på hela året känns det som liksom.
Det var liksom så himla fint.
Nej, det är inte så jag menar, alltså det är liksom lite svårt att beskriva.
Alltså det var liksom typ bara du och jag där, typ helt tomt liksom.
the closest equivalent in english is "like", and just like "like" you should try avoid saying it too much if you want to use proper swedish. though if you hang with young swedish people you will hear this word, "alltså" and "typ" in pretty much every sentence they say haha.
I use this word way too much hehe. my teacher always complains about me sayig "typ" and "liksom" all the time :)