I am admittedly deeply inexperienced in designing board games, but to steal a concept from Civilisation V (and likely some of the other games too, since I wouldn't assume this is unique to the fifth iteration of the game), what about having some objectives that rely on multiple players to contribute for there to be any reward, with greater contributions leading to greater rewards?
To give a simple example: an expedition to explore uncharted islands requires at least 10 ships in total to undertake, each with complete crews and equipment.
If the players don't collaboratively contribute a total of 10 ships, with crew members and equipment, no-one gains any rewards.
Assuming that they do meet the minimum requirements for the expedition to go ahead, the player(s) who contributed the most ships receives 10 Victory Points, with 5 points for the second largest contribution and 2 points for the third largest.
I think this has the benefit of incentivising contributions, encouraging competition between players, while also asking players to judge how much of their resources they can commit and whether they can compete with other players.