First you need to understand the coordinate system. Starting at zero lat/long North is heading zero and latitude increases. South is heading 180 and latitude decreases. East is heading 90 and longitude increases. West is heading 270 and longitude decreases. The North Pole is at latitude +90 and the South Pole is at latitude -90. Longitude ranges between -180 and +180. Just like here on Earth in real life.
My recommendation is to get to the correct longitude first, then turn and find the correct latitude. Doing it in that order means you're flying straight lines both times. If you did latitude first, you'd have to fly a curved course to maintain that latitude while finding the longitude.
After a while you'll get a feel for how it works and can start cutting corners (literally).
Also, keep flying between the OC and DROP altitudes. The higher you are the faster you'll go. Remember that the surface curves away from you and your altitude will tend to increase unless you keep pushing your ship's nose down.