Here are a few tools that are often overlooked by beginners.
Rotate: When you select and start to rotate an object you'll notice a blue rotation icon shows up. You can move the icon to rotate an object about any origin.
Mirror: When you select and start to mirror an object don't overlook the fact that you can DRAW any axis you wish to mirror about.
Stacked Walls: Does the width and material of your wall change halfway up the elevation. You can select the Stacked Wall from the drop down list and edit it to suit your needs. Remember that you have to create the two wall types separately before you can add them to a stacked wall. If you want to break up the stacked wall after it's placed just right click on the wall and select Break Up.
Leaning Walls: Do you have a wall that leans? If you go to your tools palette (Basics, View, Modelling, etc) right click on it you'll notice there are massing tools. Create a mass of the volume you want and then use the Wall By Face tool to create walls from your mass volume.
VH Command: Select any object and type VH. You'll notice that every object in that category hides from view. This is a fast way to hide whole categories without having to go to the Visibility/Graphics Overrides (VG) dialog.
Drawing List: Did you create a drawing list and you don't want that sheet to show up on the list? Select the sheet and go to its properties. Then uncheck "Appears in Drawing List"
Select All Instances: Want to change a wall type globally. Select one of the walls and right click. Select All Instances and you can change them all at once. When selecting all instances of a detail line be aware that the tool will include detail lines in ALL views.
Filter Selection: Select everything with a fence select and click on the Filter Selection Icon (next to Press + Drag). You can now filter out all the categories you don't want selected.
Browser Organization: Did you know that you can change the organization of your Project Browser? Go to Settings... Browser Organization and change or add filter rules for organizing the directory tree that appears in your Project Browser.
Tool Palette Extras: Right click on your left hand tool palette and you'll notice there are Area Analysis, Massing, and other tools available.
Thin Lines Tool: Are you having trouble seeing your work because the lines are displaying too thick? Go to View... Thin Lines.