In reply to Andre.

Hey Andre,

Thanks for your reply.
I'm definitely not going to use Envato as my main source income, because so far I'm freelancing on graphic/web design which is working really well for me. I'm looking to get into Wordpress because I have a passion for it and I really miss the days when I was fiddling with code on 2.3 version, trying to get my theme look like I wanted in CSS, PHP, HTML and so on.
That experience was what kept me coming back for more and optimize my theme.

I remember going over hundreds of free themes until I found one that I liked, so that's why I want to get into business. I want to provide themes that are focused on certain niches, while having a quality code, no extra dozens of features like on Themeforest.

I'm looking to sell on Themeforest because of the large marketplace and yes, it's about money too. If there is one place where you can get some passive income, Themeforest is a good place to go.

I was also looking into underscores framework and it seems interesting so far.
Anyway, is there a place besides Wordpress Codex and WP Tavern where I can read (something like a blog) about how to keep my theme on Wordpress standards and practices like building plugins instead of integrating everything into functions.php?