I've found out several tricks with Mail that can help you with your workflow.
Command key will give you the effect of toggling; It means that you can change the select/deselect status of certain items.
When keystrokes Command-A is pressed, all items will be highlighted. It's powerful, isn't it? And one more thing, with this keystrokes, all highlighted items won't be marked as Read, they will stay in their current condition. It's all about using Command key.
Second, when you're holding the modifier key Shift and clicking on other items, all the items in between will be highlighted inclusively.
Third, highlighting with your mouse is also possible and it's easier. It's a bit tricky here, you need to drag your mouse vertically, either up or down, in order to highlight several items in one shot. Drag your mouse to other direction will result in you dragging the items instead of dragging the selection.
You can combine the mouse trick with the Command and hopefully filtering your mail comes in handy.
Clicking on certain item, of course, will result in it's being opened in a view pane. However, with a several understanding on modifier keys, you can perform different action.
This is the essence you got from utilizing the Double-Click of your mouse. When you have selected more than one items and you Double-Click on one of the selected items, all the items will be opened in a separated Mail windows, isn't it useful?
When Option key is pressed and Double-Clicking is performed on certain item, if it's performed on Mailboxes, you'll be granted access to instantly reply the message, and if it's performed on RSS, you'll be instantly directed to the site.
Simple Drag-Drop is always the easiest way to attach items (links are included). And eventually you will find out that Command-I is the best way to attach a whole page of your browser to Mail composer. The most interesting part here is, you even can modify the content of the attached browser page.
Some articles taken from our resource base, tightly related to current article, to empower you with more knowledge on tweaking the most out of your Mac.