Backface Culling

To be sure your model's normals are facing outwards instead of inside, hit the Backface Culling button that is located; under the 'N' toggling menu -> the one that starts with Transform on the top. scroll down towards the 'Display' section and check the Backface Culling box underneath the shading section starting with 'Multitexture'.

Now you can see the inverted normals and the holes in your model if there are any.

Next is the selection of your model. Highlight it in Object Mode and hit the 'Tab' key. You're in Edit Mode right now. Then press 'A' to select all the faces. If it doesn't turn orange, hit 'A' again.
Everything highlighted? good! Now press CTRL + 'N' , it automatically turns all the faces outwards.

Using modifications like subdivision and more in animation.

http://blender.stackexchange.com/questions/164/can-modifiers-such-as-subdivision-and-array-be-animated

I want to make lids to a box or detach a rectangle from a wall to be a door aka detach an edge by ripping.

Select said edge and rip via V key.

Watch this: http://www.youtube.com/watch?feature=player_detailpage&v=K8RlSiNBsVg

How do I Vertex Paint?

You be patient and watch this nice lady tell you about it. http://www.youtube.com/watch?v=qqoFIvJXJrs

Fixing Normals a.k.a. Why do some of my faces look transparent?

Ctrl + N that fool to make Normals Consistent.

Select a loop a.k.a Double LMB in Maya

Alt + RMB while in Edit Mode. Link: http://wiki.blender.org/index.php/Doc:2.4/Manual/Modeling/Meshes/Selecting/Edges

Instantly switch between Vertex, Edge and Face selection while you are in the edit mode.

"Ctrl+tab 1, 2 and 3. Come on man, it is in the menu if you look." -A guy who reads the manual before he does things.

Link: http://blenderartists.org/forum/showthread.php?213343-Keyboard-Shortcuts-to-switch-to-vertex-edge-face-Select-Mode