I think the best way to learn to judge sheep is...looking at a lot of sheep.
I was lucky that I had many years worth of looking over tons of sheep near my hometown of Missoula Montana. We had lots of opportunity very near Missoula to look over rams. With a little practice you can start seeing differences in mass, length, etc.
I dont think sheep are that difficult to judge when you have lots of time to look them over, compare them to other rams, etc.
I've also been fortunate the last few years to have the opportunity to hunt sheep with a good friend in 2004 and my Dad in 2005 in MT.
Heres a look at the best ram I could find in my Dads hunting unit this last season out of 52 different rams 3/4 curl or larger that I looked at. Of those, there were maybe 6-8 that would have scored in the 180+ range. This ram was with a herd of 16 rams and there were 2 that stood out from the crowd, this one, and one other that probably scored within a few inches of this one:
I spotted this ram while my Dad was working and I told him that I thought it would score about 184-185, based on my estimates of 16 inch bases and horn lengths of 40 x 38 with decent mass throughout. I was pretty close to that, and thankfully 3 days later I was able to confirm my estimates were pretty darn close.
Heres another look at the mass, which is crucial in score. The first 2 mass measurements are over 15 the third quarter is 13. This ram doesnt carry the mass all that well, but probably as good as can be expected for a 7.5 year old ram.
http://photos.imageevent.com/buzzandpat/newpictures/websize/IMG_0745.JPG[IMG]
The final net official score was 183 4/8, gross score was 184 and change.
Heres the sheep my buddy killed in 2004, very different ram. The horn lengths were both slightly over 40 inches, but the mass was just a pinch over 14 at the base, but the mass didnt carry all that well. This ram was 10 years old, and net scored at 179 5/8. A really pretty ram and he was with a herd of 8 rams. There was one other ram with much shorter horns (probably 37ish) but was broomed heavily, also very old. We debated as we watched those 2 rams about which would score better. We ultimately decided that the score was about the same. My buddy liked the look of this ram better, so took him. This last season a hunter killed the heavy ram my buddy passed on, and it was right at 180 and was 13 years old. So again, we were pretty close on our estimates.
[IMG]http://photos.imageevent.com/buzzandpat/huntingpictures/websize/tomsram3.jpg
Now for the most important part...
I personally think score has ruined more sheep hunts than anything. The best advice I can give you is to go out, look over a bunch of sheep and decide what YOU want in a ram.
Flaring horns with lamb-tips, old broomed heavy sheep, etc.
If you see a ram that you'll be happy to look at the rest of your life...by all means take him and dont worry about the score.
The two hunts I was on the last 2 years were great, as the score wasnt that important to either my buddy or my Dad. The types of rams they wanted were probably going to score well as they just wanted mature rams.
Enjoy the opportunity and beyond score, horn length, or anything else, just have fun.