Practice is the key.. and know for a fact that the first iteration of your ride wont be perfect.
Heatmaps are your friend, don't just focus on Excitement, Fear and Nausea, the other Heatmap options will also offer good clues as to what's going on with a ride.
Its all about gentle tweaking then testing, and repeat. Don't make large sweeping adjustments, tweaking it, gently.
Have fun, if you find you are getting frustrated.. Save and walk away.
.
Right now, there is no "perfect" method.
I fully expect the Coaster Physics Engine to be slowly adjusted over the next few months (a reason why I try not to go into specifics as far as Coaster design in PC [wink] ).