Formal:
* Gosto de... (This is the most common and formal way to say "I like").
Informal:
* Eu gosto de... (This is also common and more explicit about the subject being "I").
* Adoro... (This means "I love" and is used for things you really like).
* Curto... (This is a slang term meaning "I like" or "I enjoy" and is more informal).
* Acho legal... (This means "I think it's cool" and is used for things you find interesting).
Examples:
* Gosto de chocolate. (I like chocolate.)
* Eu gosto de música clássica. (I like classical music.)
* Adoro viajar. (I love traveling.)
* Curto jogar futebol. (I enjoy playing football.)
* Acho legal a sua ideia. (I think your idea is cool.)
Remember to choose the expression that best suits the situation and your level of formality.