Q for Mortals is the best resource out there to start learning q. It's thorough and covers all the basics in detail. Once you have read that, you can start looking into other resources on the web.
I use Kx Reference page for quick lookup on syntax. It's a very good and quick resource but sometimes it can lack some details.
There are other blogs/sites that are helpful too...some of them are still being updated whereas others (blogs) are not being updated anymore for some reason.
Once you get comfortable with q/kdb, start reading First Derivative's White Papers. They are good for understanding kdb architecture and all the magic that happens under the hood.
Here is a list():
- kdbfaq – great blog covering diverse topics
- timestored – nice tutorials covering basic concepts
- Life is a list – Great blog on q with several hidden q features
- qKdb - This one is more analytical and only has few posts.
- Enlist q - I manage this blog and try to update it on a regular basis.
Hope this helps!