First of all I don't know why there is a Subdivide Surface modifier when it does the same thing that the Multiresolution modifier does. But I listed it anyways however I would just always use the Multiresolution modifier, In fact, I don't know if I can recall a time I was using blender and didn't use this modifier.  It's a beautiful feature that allows you to do to different levels of subdivisions. Even more so it gives you options of what level to subdivide in the display (Preview) in sculpting (Sculpt). I don't apply this modifier until the nearly the end (as you should for many modifiers) and its powerful to be able to constantly switch levels of subdivisions to work with. So for a square 

Think of an array as copy and pasting your object, only with control of how many times to paste and where to paste. Any scene with repeated elements such as a fence or leaves on a plant are perfect to use an array on. 

One part of art that makes things look beautiful is symmetry. With computer modeling you can mirror your object to make it perfectly symmetrical.  Not only does this look great but it also saves you half the time because you only have to do one side. Keep in mind that you can mirror over any line, so you can make complex patterns easily. 

Let's say that you have a straight road that you want to go on a hill. With the curve modifier you can command a 3d object to move onto a curve. 

If you want to put a texture on a model this is the modifier to use. First you will have to subdivide your model into really small faces to get the detail. So this should probably always be the last modifier to use. Then you can add an image that will repeat itself to texturizing your object. It can be really neat. I texturized my phone case i 3D printed to give it more grip because smooth PLA is quite slick. 

This is a great way to import a CAD model and then add a texture as mentioned above. Remesh modifier takes your model and tries to redo the geometry, to retopologize it. Most likely it will not be the best geometry and it's better to manually retopologize, but it can be useful if you just want to do something like texturize it.

See this post for more details: Remesh Tool

Think of this modifier as a way to join 2 objects together. You can combine them, intersect them so only what intersects remains, or cut out of one object where they intersect. Although I will warn you that this leave really funky bad geometry that may need work. But overall this is a very easy way to combine to objects.

See this post for more detail: Boolean Trouble

Please leave your comments.

and as always thanks for visiting,
The 3D Printing Ninja
3DNinjaneer@gmail.com