ADSENSE For Beginner

Hey Adsense gurus.

Just got my adsense approved today. Now is time to set up ads display and have some options getting me confused.

What is the best practices to be safe and get best results for ad placement?

1) By site - Auto ad placement
2) By ad unit
3) Global settings

I got approved two days ago, I've been experimenting a little bit and I think By Ad Unit is better overall, it gives you more control over the ads and the placement, and some of them can be customized to fit your layout (design wise).
Best way to describe Auto Ads is Plug n' Play, you have little to zero control and it can make your website look spammy.

Edit: also, most of the articles I read state that the best placements are often in the articles (after 2 or 3 paragraphs) and at the end of the article or right below the header.

Any info/tips from experienced users is appreciated!

How mat articles you have in your site