In Italian, how you share your opinions can change based on whether the setting is formal or informal. Let me break it down for you based on my experience:

Formal Expressions:

• Use “secondo me” (which means "in my opinion") carefully.
• Instead, you can say “Io ritengo che” (I believe that) or “È fondamentale” (It is essential).
• These phrases are usually more respectful and polite, especially in work situations.

Informal Expressions:

• In casual settings, it’s okay to say “penso che” (I think that).
• You can make it more personal with phrases like “a mio avviso” (in my view) or simply use “credo” (I believe).
• This language is more relaxed and can even include slang or local words.

In short, the way you speak changes from being neat and professional to more relaxed and friendly. This is really helpful depending on the situation you are in!