Just like other 3d programmes XPS supports a variety of textures you can use to make your models look good. If you do not use any textures, XPS will render your models plain white and that doesn't look too good.

The most common textures that come with a lot of game models are Diffuse, Normal and Specular Map. Often you need to edit the original textures for the model to look good in XPS. These tutorials will cover common fixes you can do to original game files that look weird on default.

What is the reason though? Shouldn't the original files show my model exactly like it is shown ingame?
The answer to that question is unfortunately no. Games use shaders we don't have in XPS. They can read textures differently and often this is also done to save space and processing.

While Diffuse textures are mostly fine, Normal maps often turn out to have a channel inverted or they need some copy-pasting of random channels overall. Specular maps can come in various forms aswell. In most games they are hidden in a channel of mask maps or even in the normal maps. Very weird cases like the Dynasty Warriors games have them in the same channel as the alpha one. An explanation for some of these cases are given on the Lazy Tools release page.

You can now use the navigation on the left to go to the texture pages or click on the pictures below.
(Color: Diffuse Map covers coloring textures with masks in photoshop, Shading: AO Map covers creating them, Structure: Normal Map also includes using mini normals and masks, Shine: Specular Map also teaches how you create your own)