I know this isn't something you can just "turn on" but... personally I love it when technicals books read with a nice "flow".

For example I hate it when books read like "here's an explanation of this. Here's how you do this. Here's the next thing. Here's how you do the next thing". They read like a step by step manual.

I like technical books that read like a novel, even though you're instructing the user. If you can incorporate a "story" at the same time, you have my attention for the length of the book.

A book that I can think of off the top of my head that I enjoyed reading, and how it read, was The Well Grounded Rubyist.

I wish I could better explain what I'm thinking at the moment. Once I get done with my nights work I'll try to come back to this.