Perhaps start here:<p><a href="https:&#x2F;&#x2F;www.nngroup.com&#x2F;articles&#x2F;overuse-of-overlays&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.nngroup.com&#x2F;articles&#x2F;overuse-of-overlays&#x2F;</a><p>Then ux.stackexchange.com will undoubtedly have some useful pointers as well....<p>Although some tailored google searches will also help.<p>Back in my UX-only days, I used NN Group a lot in supplementing my own A&#x2F;B testing - it was a bittersweet relationship, as they provide a suite of analytics-based trackers on many of the websites I visit.