Make ammunition expensive.
- In EVE Online ammunition needs to be cheap and plentiful, because of the PvE elements in the game. As far as I've heard, PvE (shooting AI controlled constructs for loot) is not really going to be a thing in DU, therefore it can be expensive enough that shooting some random newbie for a few units common materials is not worth the trouble.
The economy of PvP needs to be tuned to the point where blowing something up is only worth it for political reasons or punishing reckless greed. For example, the ammunition required to destroy the most basics of constructs should always cost more than said construct. If someone is hoarding wealth, they should need to invest a portion of it to protect it, or use some other means to make it not worth the effort, such as setting up in some obscure location.
This obviously wouldn't stop an individual from throwing away their time to blow stuff up without a tangible reward. But, when scaled up, it does prevent a significant portion of people from spending more time blowing up trivial things, than it does to acquire the tools/consumables to do so. On the flip side, there is a need for potentially lucrative targets, as well as accessibility for players to engage in PvP for fun.
There does need to be some degree of persistence for all players, so blowing someone's stuff up should be a calculated or consensual decision. It's mostly an economic problem that will require a lot of tuning to find the right balance.
I've played in many games where anti-griefing mechanics get abused, so I would first target the problem economically. Also, having an accessible and engaging combat system, where shooting targets that shoot back, is simply more fun than shooting people who are trying to gather resources or flying their first ship, would go a long way.