It helps that Firefox offers to change to an existing tab when you try to open the same page in a new tab.

Another suggestion is to not manage it. I create tabs all the time, and often have many similar tabs. There's no need to manage it, only to clean up once in a while.

(I like many tabs. A few weeks ago I performed some tab-cleaning -- 550 tabs were a bit much, as it made Firefox start slower.)

Personally i just use it for things I would like to read at some point, instead of filling up my bookmarks with 50-10 entries every day.