The example illustrated in the picture above is probably the most familiar. I know it frustrated the heck out of me when I was a beginner and learning the software. The scenario starts with created a sketch of something. For example, I begin the sketch a floor in Revit.
So I continue sketching my roof and I have some areas that have a very gradual angle. Well, Revt's snaps won't let me pull the end of my line to meet another line! ARGH!
The solution is simple. Right click while you are in sketch mode and the boundary drawing tool is activated (you will have a cross instead of a mouse).
You will notice a different menu than you are used to when right clicking. This menu has the "snap overrides" tool.
Select "Snap Overrides" and then select "Endpoints".
More often than not this will work. If Revit really feels like being fussy you may have to select "Snaps Off" first, right click again, and select "Endpoints".
Additionally, in some situations you can hit the "TAB" key instead of right click and Revit will figure out you want the endpoint... This could save you some time as well!
One more thing, if you are a keyboard shortcut type of person like me, you can also use keyboard shortcuts, SE for "Snap Edge", SO for "Snap off" and so on.
This will certainly unlock the constraints and stop you from pulling your hair out!
BIM After Dark - Volume 2:
If you enjoyed the tip above you will also enjoy BIM After Dark: Volume 2. Volume 2 demonstrates just how efficient Revit® can be in the production phases of your projects. From setting up views to wall sections, this video series will teach you how to take full advantage of your Building Information Models.