Sainath's Advice on Sunday, August 21, 2011 :
At 8 years of experience you should be strong in design. Just having more years does not mean growing in experience, to grow in experience you should have "experienced" using many new things as far as technology goes.
Please use the Microsoft Application Architecture guide to boost your understanding of Application design. Please check the below link:http://msdn.microsoft.com/en-us/library/dd673617.aspx
The guide is a starting point. At appropriate points various references are quoted, for example, to learn various design patterns. Overall it is an excellent publication. But please set your expectations right - you cannot learn app. design overnight, it is learnt over time by applying the stuff studied, facing problems and coming back to the theory to learn about alternate solutions. So do not be in a hurry and expect overnight results.
Also please check out the architecture section on MSDNhttp://msdn.microsoft.com/en-us/practices/
This is a starting point for many different learnings.