Here's a piece of text pasted from the FAQ. My personal advice would simply be to practice, to browse through the help, use google, and to post on the forums and newsgroups for specific questions.
Chris Sells, 2004, Addison-Wesley. ISBN: 0321116208.
Chris Sells and Justin Ghetland, 2004, Addison-Wesley. ISBN: 0321125193.
An excellent book for learning Windows Forms for both beginners and experienced programmers. The presentation is nice and crisp the chapter size is usually around 50 pages, presenting all the necessary details and at the same time maintaining the reader's interest in the topic being presented.
Charles Petzold, 2001, Microsoft Press. ISBN: 0-7356-1370-2.
Charles Petzold, 2002, Microsoft Press. ISBN: 0-7356-1799-6.
This is an excellent book for both Windows Forms and GDI+. Petzold writes lucid prose.
Ian Griffiths, Jon Flanders & Chris Sells, 2003, O'Reilly. ISBN: 0-596-00360-9.
Every page of this book is packed with useful information on getting the most out of Visual Studio .NET 2003. Written by experienced developers and trainers, it is accessible to beginners and invaluable to accomplished developers.
James W. Cooper, 2003, Addison-Wesley. ISBN: 0201844532.
This is a good book to learn about patterns through a C#/Windows Forms lens. Several of the samples are UI related and use Windows Forms.
Eric White, Chris Garrett, 2002, Wrox Press. ISBN: 1861006314
The title of this book is kind of misleading. It is an excellent introduction to GDI+. In addition to GDI+ there is also information on control designers that will be useful to control authors.