elliptical machines

I don't bother with the bells and whistles. For steady-state I settle in at a resistance level that gives me a heart rate of 65ish% of max. If I'm doing intervals I use a setting for my high-intensity sections that returns 85-90% of max.

^^^^ This.

I get on the machine, do a 2-3 minute warm-up to get my heart rate going a bit, then set the resistance so I feel like I'm going in concrete and start cranking like I'm being chased by rabid wolverines. After a very short period of this, my heart rate is up between 65% and 85%, and I adjust cadence or resistance (depending on how my legs feel that day) to keep it there until I run out of time.

MAX BURN. I hate the elliptical but in the winter it's a great way of maintaining endurance, so I love the results of using it. I try to make every second spent on it count.

PS: If you're just starting out, I'd suggest doing something similar to my previous post but at a pace you are comfortable with. Get on it and set the resistance moderate (the elliptical I use goes to 20. I'd start around 7-ish - just to the point where you start feeling the resistance a bit). Get your heart rate up slowly into the "cardio" range and keep it there as much as you can.

The "fat burning" range is really a scaled-down version of the "cardio" range for people who have plenty of time and want a workout they can sustain for hours. I have limited time on the elliptical so I blow right through "fat burning", I burn more in "cardio" anyway.

The key is to make sure that your legs are about as sore as you are overall fatigued. So play with the resistance until you run out of steam about the time your legs start absolutely screaming at you. That way, you're training your leg muscles and your cardiovascular capacity at about the same pace. As you progress, you'll find you need higher and higher resistance to challenge your legs sufficiently.

And stretch afterward. This really helps prevent soreness and makes your legs feel great. Any set of decent runner's stretches is fine.