Azureus has so many settings that its hard to figure out how to optimize your download speed. I think I’ve settled upon some settings that work pretty well (after reading through many forums with posts containing highly uninformed speculation)
I have a 1.5mbps down 768 kbps up DSL line. So I set my max outgoing bandwidth to 50 KB/s, max upload slots per torrent to 8, max simultaneous outbound connection attempts to 100, max connections per torrent to 0 (unlimited), and max global connections to 500. It seems like maximizing the number of connections per torrent is the thing that makes the biggest difference, especially for torrents with many seeds and peers.