I track elk all the time. The main thing is to keep the wind right, and don't follow "In their tracks" I will usually try to figure out which way they are heading then parallel them, stay 1-200 yards off of their track. Once the elk spread out and stop traveling you are getting close, this is where you will find a lot of freash green stuff and wet puddles of urine. I sometimes pull out at that point and come back in an few hours and try to be there when they start milling around again.
Just a couple weeks ago I did this on a herd in Wyoming, I traked them from daylight at 11:00a.m. I pulled out and came back around 2:30 p.m. about 30 minutes later less than a 100 yards away the herd bull bugled, seconds later he was 25 yards in front of me and bugled again. He never offerd me a shot, he also never knew I was there. That was the highlight of my Wyoming elk hunt.