I wanted to post this as my 1000th post but it's 1006th now... Yup, I forgot.
I have been doing SEO for my sites for 3 years now...
...and I have been testing on-page SEO techniques in different ways, different environments and even for really long tails keywords(single variable test)
I have a few clients that pay around $2k-3k a month for this stuff (yup just on-page)
Here's a check list of what I do for my and my client's on-page + technical SEO:
- Fast site speed is must (technical stuff), higher the crawling speed higher the rankings(well you should always strive for faster pages than your competitors)
- Setup Google console for site issues.
- Setup your canonical url. Check yours by typing " info:site.com " on google.
On page part:
MD and PMD still work!!
but you have to make it into a brand by nap syndication, entity stacking and branded links(which almost 80% people don't do, I would like a service which does this here, it will save a lot of time)
- H1/title must have exact keyword.
- Brand name in title tag works really well. Eg: best coffee maker reviews by coffee makers. (Or just use yoast for this)
- Meta title should have an exact keyword.
- Meta description doesn't matter much(no great tests till now)
- H2 must have an exact keyword or longtail related to the main keyword. (never use H2 for useless terms like contact us, about us)
- H3 should have a partial match keyword or LSI or longtails or trending terms on google... I love to use h3s to explain my content. (Most people use H2 for that, good but why do you want to confuse the Google bot?)
- I have not tested h5 and h6 ever.
- Always add the main keyword in first 200 words.
- Lsi should be added in first 500 and at the last.
- Outbound links to Wikipedia etc should be at the last(reference maybe), internal links works better when added in first 200 words.
- Exact keyword in alt tags is must( don't just add: Samsung s9 review as tags, no big no. Write 100 words about it and add the keyword in first 10 words if possible) 1 picture = 1000 words
but you know
100 works just fine though 
- Silo or no silo doesn't matter, but the internal linking should be on point. Trust me when I say that silo helps in proper internal linking, that's why it works so good. Relevancy is transferred with internal links... Plus silo helps in structuring the site, so I recommend it if you have a big site or plan to make an authority site.
- Content on the site, varies with niches/ type of content etc ( if it's a BMI calucalcul or coupon code, adding 50 words is enough, more content won't give you the ranking boost you need as google knows... And if you're writing a guide to do something then FAQs are must, so these things come to you by observing competition, and by experience)
- Increase dwell time (backlinko guide)
- Hyperlink h3s and lists when ever you can helps you score the site links

- Menus should be exact keywords where ever possible as menu links are crawled a lot.
I think of pages on the internet like a research paper outline:
H1 - Intro
H2 - Subtopic Paragraph
H3 - Sub topic of the subtopic
H4 - Conclustion
Pull up some research papers and see how it is done. I am writing a research paper for my dissertation so I know. Trust me
PhD fucking suck... But it has helped me in optimizing my content a lot.
Follow whatever these research papers are doing:
https://scholar.google.co.in/scholar?q=artificial+intelligence+research&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwiyr-P25NXaAhUMqI8KHddcCSIQgQMIJDAA#d=gs_qabs&p=&u=#p=ywslJ0HMWn0J
Remember:
On-page should be whitehat, should have content which reads like human: crappy content gets penalized!
Don't judge content by its grammar, spelling mistakes etc but the content should be judged according to the value it gives. If a person will learn something after reading the review then it's great.
Eg:
If you are writing a review:
Write the experience. Don't write the useless feature the product has even if its unique.
Real images work better than product images.
I have seen 25% conversion rates on my review articles with this
Offpage can be blackhat, I like blackhat

faster work can be done and if you're penalized, you can get out of it by disavowing a few links.
If I have missed anything let me know
You can ask for questions in the comments...
Please don't PM me.