"I like your dress."
Translation:Podoba mi się twoja sukienka.
no. It just means I like her dress. Podoba mi się Pani sukienka, would be for "your dress" in formal context.
"lubię wasze stroje" or "Podoba mi się wasze stroje" - In English I might say this to a well dressed group, such as a musical band, for example - 'I like your dress'.(?)
I added "strój" in singular, but can it really be used for plural, won't in need to be "dresses" for "wasze stroje"?
In your second sentence, the verb needs to be "Podobają mi się", as you used plural 'stroje'. Podoba mi się wasz strój / Podobają mi się wasze stroje.
(owning one dress by more than one person is less probable but not impossible)
I tought the "sukienka" had to be in "biernik", so put "podoba mi się twoją sukienkę". So that is not correct then ?
I understand why you thought that, the thing is that there are two options:
Either the literal translation "Lubię twoją sukienkę", which sounds rather strange without a specific context - it sounds as "of all your dresses, I have always liked this one and I have nice memories connected with it, etc". And this sentence would take biernik indeed, as "lubić" needs biernik.
Or what makes more sense here: "Podoba mi się twoja sukienka", ergo: "I like your dress" as in "I think your dress is pretty". "Your dress is pleasing to me" seems like the closest equivalent in terms of grammar. And in such a sentence, the thing that you like is actually the subject of the sentence. So it's put in Nominative.
'Podoba' isn't first person, but third person :) You could translate this construction as 'it appeals to me', where 'appeals'/'podoba się' is in the third person and 'to me'/'mi' is an indirect object in dative.
Is there an acceptable solution that starts the sentence with twoja sukienka? Is podoba się used like gefallen in German?
"Twoja sukienka mi się podoba" should work as well. Indeed, podobać się is very similar to gefallen.