Violence, for a political aim should be cold and calculated, not emotional. It should also play second fiddle to non violence and communication.

The Irish troubles are a good example. The IRA forced the British government to listen to the politicians. The non violent protests and marches gave popular backing to the political process.

In a sane world, politicians know that violence is an option, and pay heed to the non violent methods before it escalates. This is what has happened in a number of non violent political movements. The option of escalation cannot be taken off the table however. It provides the silent bite to back up the bark.

The biggest thing to avoid is emotional violence. Smashing up shops in a riot might feel good but achieves very little. It burns the good will of the public. Instead it needs to be focused on a target, with minimal collateral damage. Particularly collateral deaths/injuries to the general public.

Ironically, the recent burning of a warehouse is a good example. Little to no collateral damage, but significant damage to its target, with a strong, stated reason.

One thing to note. Disparaging non violent protests is a definite bad move. Those protests provide both cover to organise, and a weathervane on public feeling.