If you're prepared to spend real money on getting a good ratio then something I've done in the past is pay for a seedbox for a month or 2. You can find them for as little as 5 euros a month. Many offer gigabit speeds meaning that if you pick the right torrents your ratio can go through the roof. I haven't needed to use one for 3 or 4 years now, but I think I managed to seed about 2TB in a month. I'd just fill it with busy torrents, and every couple of days remove the ones that weren't performing well and replace them with others.
I'm on rubbish ADSL where I live right now, so my upload speed peaks at about 1.5Mb/s, so there's no way I can seed enough to keep my ratio up. I was going to go down the seedbox route again, but I'm hoping to move withing the next few weeks and the speeds at the new place are great.