While I'm sure you've heard most of these, here's some general tips:
- Seed as many individual torrents as possible. This increases the odds one or more will actually be active at any given time. Currently I have 115 seeding on BakaBT, and my upload pipe stays maxed most of the time.
- If using a decent client (for example, Vuze, qBittorrent, uTorrent), increase both your maximum total connections AND max connections per torrent to the same number; also make sure "Use more upload slots if upload speed is < 90%" (uTorrent's phrasing, other clients will vary) is enabled, as well. Don't worry, this will NOT cause one torrent to choke off all of the others! Instead, if few torrents are actually active, they can use many more of the available connections.
Most relatively modern PCs will have no problems at all running 500-1000 total connections at once, but you CAN start to chug your system if you overdo it. Just keep an eye out, it'll be obvious if it happens. Currently, on a Core2Quad at 3.0 GHz, I can run at least 1000 connections without noticeable framerate hits when gaming at the same time.
- Try to especially target torrents for download that have just been released and are still in their non-Power-User "blackout" period. This almost guarantees a decent positive ratio boost.
- Sort the torrent pool by leechers, and download those that have the most =) .
Make sure, BTW, that you cap uploads at 80-85% of your actual maximum capacity, at least as long as you're downloading anything or using the internet for anything else. If you max your actual upload capacity, your DOWNloads will suffer a great deal, as well as general net activity; this is a limitation of TCP/IP.
Hope at least some of that helps! Good luck.
Edit --> Frankly, I have a ratio of 2.087 currently (4199.25 GB up, 2012 GB down) without actively trying to select any torrents for upload "suitability". I mainly just plain keep as many seeding as I can for as long as possible, while allowing many connections ^^' .