Yossarian,
Find a field to land at that has the Visual Approach Slope Indicator lights.(Most major airports have them on one or more runways) Start your approach a few miles out from the field and watch the lights as you descend. In a Cessna 172 start say 5 miles out at 1500 feet altitude. Line up and hold altitude as you approach the strip. Watch the "VASI" lights on the left edge of the strip. These are for lights that will show red, white, or a combination of the two. If you see two red and two white, you are on the glide path for that field. If you see all red you are too low, all white means too high.
Trim does play a MAJOR function here, but get the basics for landing and THEN work on using trim.....
Using the lights in this way will give you a feel for a glide slope. You can turn that into a practice for just about any aircraft. Its not exactly right, but close enough for flying a cartoon aircraft that doesnt incur insurance premiums......