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I am learning my way around SEO, having always used professionals for it in the past on previous businesses i have decided to do it myself and learn more about it. Now the dilemma i am up against is i recently changed some of my permalinks on quite a few main pages throughout the site. The site launched in April this year so we're quite new.  The problem is since my last change i have not seen any increase...a decrease which in fact hasn't recovered at all. Having now analysed them in more depth and read up more on the whole subject of SEO, (which is endless) i have put together a complete new strategy; with this increased understanding of what i am doing (but by no means conclusive) i want to complete a full overhaul on all SEO (via Wordpress which i use along with YOAST SEO tools), ensuring i have all my keywords, permalinks and descriptions spot on throughout every page, post and picture. I spent a lot of time mapping these out, ensuring there is no Focus keyword duplication, and that the site is relatively flat in terms of its layout. What i am unsure about now is whether changing my permalinks again is a bad thing to do? 
Could it permanently damage my rep going forward?
Should i just focus on my content and keywords/descriptions? I am at a loss as i don't want to do irreparable damage to our reputation.  The site is still reasonable easy to manage so changing now is the best time to do it, but if changing the URLs is a waste of time then i may just forget that and just work on the keywords, descriptions and content. Advice is 'oh so welcome' 🙂