Best methods are good bounty campaign!
Problem is what constituted "good". Bounties and airdrops are the main reason this forum has degraded tremendously. I've been lurking for years, but decided to join, and still mind boggling how bounties and airdrops are. Literally thousands of people wanting "free"money.
Of these thousands of bounty hunters, a huge number of bots and multiaccounts. If we solve the problem of automatic recognition of these multiaccounts, it would be much easier for honest bounty hunters and developers and managers of bounty campaigns.