All great advice, I would like to add a few things that work for me...

Stick to your niche as tightly as possible, and don't be too general unless you want a lot of work promoting it. The tighter the niche, the more traffic you'll get for it with less effort than a general "gay porn blog".

Have some personality. Throw a little of your character (or a manufactured one) in with your posts.

I would disagree on your suggestion of only one or two paragraphs. Of the blogs I have, the ones with lengthy text posts here and there pull in the most traffic. Write about anything related.
The more text there is the more Google will value the site as a provider of information. One of the biggest mistakes affiliate bloggers make is their lack of original text.

Add correct tags to images before you upload them. Then make sure those same tags are added in the right place for that image.

I would also disagree with starting out with a network. As long as you can keep up with the posting, have as many as possible in various niches, and experiment. One of them will do better than the others, and then you know which one to focus on and build. You can still support the others and update less frequently, but the wider the net, the more traffic, and the more sales.

It might be predictable for me to say it, but if you can't keep up with posting on a blog every single day with enough original text, why not hire someone else to help you out with it?
It doesn't cost a lot to have a decent writer creating your text for you, and at least you'll know you're getting daily updates and you can concentrate on building links, or work on new projects.