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Hello. I have a lot of pages that I'm optimising. The ones I'm focusing on right now is already ranking, but the URLs could be better (they don't include the keywords right now). However I'm worried that if I change the URLs they will drop in rankings or have to start over. I would of course set up 301 redirect, but is there more I need to do? What is the best way to change URL for already ranking pages?

Should I use canonical tag in these cases? On the page itself (with the tag pointing to itself) On pages that doesn't have duplicate versions