Another little tip. Targeting pod; SPI, laser and you.
When you create SPI (TMS forward long), it creates a coordinate. But there is a little problem. It doesn't recognize elevation well or objects in front of "coordinates".

On this screen I'm pointing at a building. Or so it seems. Actually I'm point behind this building. Targeting pod right now just doesn't see it. So if I enter that as SPI and drop GPS bomb, it will be a miss.
How to solve this? Press NWS (nose wheel steering in flight turns on the laser) and then create SPI. As you can see on this screenshot, now distance to building is 4.3 and coordinates are exact.
Good luck!
Edit: Terrain also causes problem when selecting coordinates. So whenever you want to create SPI, press and hold NWS then TMS forward long.