In my opinion, the Force-Bubble Shield is one of the coolest out there . Just recently I've been experimenting with Force-Bubble Constructs, and the shield version is very useful and holds up against a lot of force. I can be used in combat or in any situation where you need to physically put force on an object. The downside is that it is pretty advanced and takes a lot of time to make (in most cases). Skill in telekinesis is useful.
The visualization is fairly simple but tedious. The one I use is to visualize a bunch of "psi-bricks" stacking up and forming a brick wall around myself. You'll also need some "psi-mortar" as well to stick it all together .
Also, to incorporate the idea of force, I visualize a bunch of arrows pointing outwards on the bricks. In physics, force is usually shown by an arrow, so it works well for me (having a somewhat scientific mind). Think of something that means "force" to you and use it. The key isn't necessarily the visualization, but the practice. This shield takes a lot of skill to construct properly.
The Force-Bubble Shield is extremely useful and powerful. While the previous combat shields address the issue of dealing with an attack, the last shield's purpose is to help you not get in situations where you'll get attacked. It's known as the Cloaking Shield, or in some cases, the "Hedge" Shield.
