What is and isn't acceptable forms of protest?

No violence, no property destruction, a permit (if required for shutting down streets).

As long as you can ignore it is ok. /s

Unacceptable: that which violates the law or encourages others to do so.

Acceptable: just about everything else bearing in mind empathy and mutual consideration of others.

It would differ based on setting.

The idea that protests cannot be violent is strange to me. non-violence is a particular strategy, not a requirement.

Malaysia is probably one of the few countries with actual successful protests. We've had multiple government changes from it, including the British. And peaceful measures worked better in getting rid of communism than violence.

What's important is to show that everyone agrees on a policy. Politicians are social creatures. Colonists care about cost-benefit. Politicians only care that they'll hold on to power; nobody wants to be backing the guy on his way down.

I think most protests are not consistent enough. Protests are a marathon, they need to be done over years, consistently. We had tear gas and chemical sprays for the first years of corruption protests, but as time went on, the protesters became more peaceful, and the police started to have sympathy for them.

A good modern example is gay rights. I'm not sure if 'protest' is the best word, but it has been done over many years and non-violently.

That said, it's not for all situations. Protesting Japanese occupation resulted in rape and torture. Violence didn't work either.

If a form of protest is acceptable, it will be ignored by the government/corporations/media unless it is to support its own agenda.

So violent protests against violent oppression is acceptable. Violence against not violent issues are not acceptable (like vegans against farmers, eco-activists protests, etc).