Polygon modeling 
Tutorials
The best two tutorials for getting familiar with Maya for creating models for real time rendering:
Available in the on-line help:

Getting Started with Maya > Polygonal Modeling > Lesson 1: Modeling a polygonal surface
Getting Started with Maya > Polygon Texturing > Lesson 1: UV texture mapping

If you need to review how to create materials (shaders) and apply file textures:

Getting Started with Maya > Rendering > Lesson 2: Shading surfaces

Low-poly count modeling article from Gamasutra - applies to a character model, but can help ways to think about other props in your environment, too.

Ideas for designing a game level using Adobe Illustrator and importing to Maya - Gamasutra
Maya's polygon editing tools

It can be handy to use 'snap to grid' ('x'), 'snap to curve or edge' ('c'), or 'snap to vertex' ('v') while creating or moving vertices.
In some cases, you need to use the middle mouse button to snap a vertex to an edge and drag it along the edge.

Get to know these tools:

Create Polygon tool
Append to Polygon tool
Split Polygon Tool
Extrude Face
Merge Vertices
Normals > Reverse
Normals > Soften/Harden

and these tools for texture mapping:

Planar Mapping (also cylindrical and spherical)
Automatic Mapping
Window > UV Texture Editor

Of course there are many more tools specifically for polygon and UV map editing, but you will use the above most often, and perhaps do everything that you'll need.

You can model with polys that have more than three sides, but they must be triangulated before exporting (use Polygons > triangulate). If you model with triangles from the start, you may have better control over the final results.

Converting from NURBS to polygons
Some models are easier to start out with nurbs curves or surfaces (as well as providing a good UV map). You can convert from nurbs to polys, but beware of high poly counts.

Consider using the "General" tessellation method option (the default is "standard fit") and set the initial tessellation controls to "Per Span # of IsoParms" and set the divisions to a low value or even 1.

This will give a more uniform result based on the curves you worked with in the original nurbs model.
Consolidate your models:
Polygonal models are often constructed out of separate parts, such as this example of a chair made of resized cubes and grouped together.

When exporting to Virtools, the group will remain intact. However, if you are not going to manipulate any of the child objects individually in Virtools, it can be more efficient to combine all parts into a single entity. In Maya, use "Polygons > Combine".

Also consider deleting unseen faces, such as the bottom of the chair legs or underneath the chair seat. The polygons will add up as you fill a building with more furniture.