Last year I got a new job and spent the year running all the tests we've done on DistilledODN (an SEO split testing platform).
It's changed my perspective, taught me a huge amount and I'd like to take people through all the different lessons I've learned (19 of them in fact).
That's everything from: What sort of effect do basic SEO changes? Why is changing your title tags possibly a really risky move? How and when has structured data helped? How important is freshness (and can you fake it)? Does testing change your relationship with a client? Should you put emoji's in everything...