Windows Phone 7 is hot right now, and I'm getting a ton of Qs on how to get started. Many different ways you could approach present themselves, but what's the best? Actually, I don't know but here's DevFish's Top 7 Steps to Windows Phone 7 Development ...

1. INSTALL THE DEVTOOLS - easy enough. Click once on the installer and down come all the goodies, including Expression Blend for WP7 and VS2010 Express for WP7. Click on "Download the Developer Tools" here , and while you're at it, explore some of the other links
2. WORK THROUGH THE TRAINING KIT - The WP7 Training Kit is a fine piece of work (if you're like me and love Hands On Labs to plod through at your own pace). Seven Hands-On-Labs covering basics, navigation, controls, push notifications, game dev with XNA, launchers, tombstoning, and more.  Download from here .
3. READ PETZOLDs FREE EBOOK - Over 11 Chapters (and growing) of top notch "petzold-level-content" with source code even - Charles, I promise I'm buying a copy when it comes out - well worth downloading and printing (pine trees are a renewable resource) - find it here .
4. EXPLORE SOME ONLINE LEARNING VIDEOS - Traditionally the old DevFish doesnt do well with online videos, but there are some good sources out there to help you along. Here's some of his favorites  - teched10 wp7 - MIX2010 (dated by still relevant)
5. WORK THROUGH SOME FUNCTIONING APPS - obviously you can learn a great deal by exploring other folks source code.  A number of people are putting their projects on codeplex for all to see.  I'm keeping a list of source code available apps I find here.  There are also some great samples available online demonstrating various techniques at this MSDN Link. Read the code and get an idea of what's going on.
6. STAY CONNECTED - subscribe to the following blogs using your favorite RSS reader (I prefer RSSBandit )
   • WP7 Official Developers Blog - http://windowsteamblog.com/windows_phone/b/wpdev/ 
   • Anand Iyer - http://www.artificialignorance.net/blog/ 
   • Bill Reiss - http://blogs.silverarcade.com/silverlight-games-101/ 
   • Brandon Watson - http://www.manyniches.com/ 
   • Kevin @Bytemaster Wolf - http://new.efficientcoder.net/ 
   • Mark Artega - http://blog.markarteaga.com/ 
   • Michael Kucher - http://klucher.com/ 
   • On WP7 Blog - http://blogs.claritycon.com/blogs/windows_phone_7/default.aspx 
   • Rob Tiffany - http://robtiffany.com/ 
   • Shawn Hargraeves XNA Game Blog - http://blogs.msdn.com/b/shawnhar/ 
   • Silverlight Cream WP Dev (added by popular demand aug 12)
   • Windows Phone Secrets - http://windowsphonesecrets.com/ 
7. JUST FOR DA FLORIDA FOLKS - furthest point of land from redmond in the usa - we gotta learn to be self-sufficient with all the hurricanes and mosquitos, you know?  - so first, we've got over 50 hardworking WP7 devs signed up for the Florida focused wimo/wp7 developer list at http://fla-wimo-dev.groups.live.com . If you're up to it, signed up for the group for a chance to interact with some of your dev peers in Florida.  Also, if you're working on apps in Florida (or for that matter anywhere in GA/SC/NC/AL/MS)? Fill out this form and get it back to me - http://cid-75364d9e73295107.office.live.com/self.aspx/publicstuff/wp7survey.docx . I'm particularly interested in release dates for your app, and any issues preventing you from getting your stuff 95% done in the emulator.  I'm trying to get a mental handle on what's cooking in the area.

Looking for more resources? Here's a nice one-stop-shop for you. My wiki (yes, shameless linkback link spamming) for all things I like WP7 is at http://dfwiki.devfish.net/technology.Windows-Phone-7-0.ashx . My wiki is where I put "all those links I couldnt throw away". It changes week by week, but hopefully you'll find something there that's helpful. And if you have a top notch resource I dont have listed, let me know at jhealy@microsoft.com  .