TO start with make sure you are using a good torrent client.
I use Bittorent and very happy with it. I know uTorrent is also very popular. So, I suggest that you go with one of those.
Next important item is the removal of the 10 connection limit from TCP.
This will prevent you from making more than 10 connection at a time and slow down your ability to download torrents. There are few different utilities you can use. I used TCP-Z and set it to 254 and that appears to work for me fine.
Next item to hit is your settings in your torrent client.
If you don't make these changes your torrent will client will slow down your PC where you wont be able to do anything else while your client is running.
Specifically change the following:
Under Connection:
enable UPnP port mapping
enable NAT-PMP port mapping
Add Windows firewall exception
Under Bandwidth:
Limit the upload rate to 15
Set Max download rate to 0 (unlimited)
Set max number of connections to 225
Max. connections per torrent to 50
Number of upload slots per torrent to 5
In Queuing:
Max number of active torrents: 25
Max number of active download 20
I have a 10.Mbit connection and with these settings I can regularly download 10 files or so simultaneously with a total download rate of 500 to 750 KB/sec.
You may want to reduce or increase the settings as per available bandwidth.