Advices for tech book writers

Charles Petzold wrote a while back about why it's not worth it anymore to write tech books.As a avid reader i'd thought to write a few opinions for tech books writers :

- don't put meaningless crap in the books. No pictures of Visual Studio, setup images, incredibly large code pieces and other crap like this. A technical book should contain only meaningful content.

- write focused books. Between 2 books on the same subject i will always choose the short one. My time is limited and usually thick books are filled with crap (see previous point). Here's a example of bad writing. I've read 2 books from APress by Laurence Moroney : Foundations of WPF and Foundations of Atlas. The first chapter of both these books is pretty much the same and it presents a history of the graphic user interfaces. Well...personally...when i buy a book about WPF i expect to read about WPF. If i'm interested in history of GUI i'll look it up on wikipedia.

- have ""hardcore"" content. Tips and tricks books won't cut it. There's a wealth of free content on the web : articles, blogs, MSDN etc. Your book directly competes with free, easy accessible content.

- the dead tree version of the book MUST come with a ebook version. Reading the dead tree version is great but the sad reality is that we can't do that all the time. I do the bulk of my reading while riding the metro to/from work.

- sell a ebook version at a considerable lower price.

- you if jump in the bandwagon of books who cover API's make sure you really know your shit. Keeping the WPF example.....there are LOTS of WPF books on the market but only a couple of them are worth reading.