Thankyou for such an informative post, I have ordered the book. The forum posting on designerstalk is pretty awesome.
No worries! Designerstalk is also an excellent place to get harsh, truthful feedback on your work as opposed to the unhelpful 'that's great' replies. That said, I haven't been on there in a while so things might have changed.
The important thing is to seek out folks who give honest, constructive critiques and aren't afraid of 'offending' you in the process. The most annoying thing when seeking out design critiques is to be told over and over, 'that's really good'.
In terms aesthetics, the most import thing is to develop your 'design palate'. Seek out excellent craftsmanship and learn to distinguish it from the mediocre. An excellent place to start is SiteInspire: http://siteinspire.com/
I would also recommend learning the fundamentals of design. Typography and grid systems are very important study areas. A great place to start is this forum thread: http://www.designerstalk.com/forums/graphic-design/42390-des...
For empirical testing of designs, I would highly recommend Lukas Mathis' Designed for Use: http://pragprog.com/book/lmuse/designed-for-use Be warned however that the print version is horridly designed, just get the .epub to bypass the ugly formatting.
And always have in the back of your mind: 'less is more'. Just because you've learned how to do fancy gradients, reflections and rounded corners, doesn't mean you should.