Old terrain but still find it useful.
After you have found yourself a nice spot and made sure you are in neutral.
1. Get in your main gun position. Make sure it is in default by hitting home key.
2. Hit the F8 key. This allows you to pan your view. Tap the 2 key on your number pad till it looks kinda like this.

3. Estimate rang to target and place pointer with mouse under target like in the above.
4. Fire your range shot. Move gun so pointer is back under your target.
5. Note where round lands. Now with your mouse move pointer tip to the center of your crater.

6. Now since I am more then couple of tank lengths away. Elevate gun so pointer is just above target. Fire & move pointer back over target with gun.

7. Now with mouse place pointer tip in center of new crater.
8. Move gun so tip of pointer is on your target. Fire.

9. Don't move mouse or gun and watch round land.

10. No new crater I am now hitting target and can fire for effect.
Once you start hitting them you can have 2 rounds in the air at one time.
This is helpful if the they have engine off. It allows you to hit them 2x before they move.
Another thing is with multiple stick modes in game . This allows you to have gv scaling set so gun can make very slow movement. Very useful for long range plinking.