Re: new to long range shooting
Both the Marine Corps and Army sniper manuals are great resources for people starting out. There are sections on distance judging in there that will help you alot.
A really good idea is to get a range finder. Then you can practice the old fashioned ways of range estimation and confirm the distance you estimated with the range finder. Over time you will get increasingly more accurate.
Although laser range finders are wonderful, they do break, batteries run down, or they won't work because of atmospheric conditions. So it is always good to have more than one way to get your range.
Computer programs you can put into a palm pilot type instrument are also a great help. They can help with both range estimation, and figuring out your elevation, lead, and other adjustments.