It is good from time to time to acquaint yourself with Microsoft best practices for the development tools/applications which you depend. As a SharePoint developer and administrator I make it a point to keep up-to-date on this subject. While I have read a number of Microsoft's published best practices, this is the first time I read the best practices for SharePoint. Designing Solutions for Microsoft SharePoint 2010 is the first book I read on my new Kindle Fire.
As developers we like to think that our years of experience will allow us to naturally know the best methods to choose when creating a new solution in any new tool or framework. This is not the case. Reality is, a method which works well under one framework may not work under the next. This is why it is important for us to educate ourselves with the best practices for each framework.
For example, you may have used SharePoint web services to interact with SharePoint 2007 via a solution created in Visual Studio 2008. This may not be the ideal method of choice when creating a Visual Studio 2010 solution that will installed within a SharePoint 2010 environment. The recommended method would be to utilize the Client Object Model or the Server Object Model depending on what you wish to accomplish.
If you are creating a new assembly for your SharePoint 2010 environment, should you install the assembly in the bin directory of your SharePoint web application or install it in the GAC? If you don't understand the cost/benefits for each location you might want to review this book.
It is inevitable that there will be a need to pull information from an external data store into your SharePoint 2010 environment. If so, you want to read up on using external list and Business Connectivity Service. BCS is new to SharePoint 2010 and offers a convenient method of connecting to external data stores. The first step is to configure and start this service in your environment then refer to this book to determine how best to utilize it.
Another new feature to SharePoint is the use of Sandbox. If you are a developer but do not have administrative access to SharePoint or do not have direct access to the application server of the farm you will have strong appreciation for Sandbox. It allows you to install your solution to SharePoint without causing unanticipated challenges should your code unintentionally become 'self-aware'.
If you goal is to manage your SharePoint 2010 environment using best practices, I highly recommend this reference.