Right click on the TMA plot and select a longer time display.
When you lock in the speed try to match up the bearing lines (newest is most important) and not worry too much about the older ones.
One trick I like is to get the LOBs to cross at two points one when you are matching the target's course and one where you are not, the target's range is somewhere between those two crossing points.
Also plan your maneuvers as TMA legs. Change your course and make 1/4 of a circle around the target to narrow down its range.
I recommend reading this:
http://www.commanders-academy.com/fo...do=file&id=147
and this:
http://www.commanders-academy.com/fo...do=file&id=143
and this:
http://www.commanders-academy.com/fo...do=file&id=141
(Links listed from Advanced to Beginner in scope.)