I am seeing a lot of proposals going on chain without proposers doing due diligence with respect to community discussion.
I therefore suggest that if someone makes a proposal, that they have to timelock YFI into a contract in connection with their on chain proposal submission.
Another alternative which I like even better is to have a sponsorship phase for all proposals where the community must collectively agree to lock 10YFI within a specified period (5 days, for example) for a specified time period before a vote even takes place. If 10YFI is not raised, then tokens are released back to sponsors. Also, in this scheme the proposer must be also be a sponsor to a minimum amount of 1YFI.
A certain minimum amount of YFI should be locked up by the proposed. The lock should last for a while, perhaps (edit: 30 days), to ensure that the proposer is committed to seeing the proposal through.
I would suggest a 1 YFI lock for 90 days should be required when submitting on chain proposals. This is to be considered counter-spam measure.