As a general rule, place your sign as close to the first bonfire before the boss area as possible. Never drop your sign right in front of the boss fog unless nothing else is working.
After some initial pointers there will be a break-down of each area by boss (since the point of co-op is to help the host defeat a boss), stating what levels are found to be the best to be summoned for that particular area and why or why not some bosses are better for being summoned than others. You may also find it somewhat useful when looking to get summoned for dueling via the Red Sign Soapstone or Dragon Eye, but are probably better served looking for a guide focused on PvP rather than co-op. Other players interested in learning how best to summon others for help or to be summoned to farm souls/humanity or just for fun may also benefit. Note: These methods were initially established to make characters able to join and progress in the Warrior of Sunlight Covenant, so those of you following this covenant will likely benefit the most from this guide.
