It is very hard to describe so I quickly made these 2 examples for you. For some reason the not heartlined one is pulling just about the same laterals, but I believe its because the banking is soo much smoother on that one. But ideally you want to heartline since the tools are there.
First, open up your editor. Go to Display then select "Display Heartline"
Heres the Improperly Heartlined Track
http://www.real-coasters.com/heartline/ ... ne.nltrack
Heres the Properly Heartlined Track
http://www.real-coasters.com/heartline/ ... ne.nltrack
Open them both up and compare. You will notice the first difference in the ENTRANCE and EXIT to the corners. On the improper one, the yellow line seems to veer off on an angle before it starts the turn. Thats because of the pre-banking, an older technique for steel coasters but a good one for woodies.
This causes laterals, you want the yellow line to enter/exit into the corner smoother and without that prebank.
The second thing youll notice is the Zero G roll. In the improper one, the yellow line squiggles back and forth. Thats the path your heart and head would follow. You want that to be straight for a roll like that. Look at the Proper Heartline, youll see the yellow line stays pretty straight and the track rotates around. Youll get the same feeling as you enter and exit the corners.
Heartlining in the real world is vital to keeping the lateral forces low for sharp turns or turns that carry alot of speed. You can get away without it in some cases (like Superman ROS at SFNE, theres hardly any heartlining because theres no sudden turns) but those are few.
Study this and if you have any more questions about what things should look like I can give you those.