The "Lazy Kerbal" approach: go straight up to get out of the atmosphere as soon as possible (stupid drag) and turn right once you pass the Kármán... Err, Kerman

The "Lazy Kerbal" approach: go straight up to get out of the atmosphere as soon as possible (stupid drag) and turn right once you pass the Kármán... Err, Kerman Line (at 70km). Start burning near apoapsis until your periapsis is >=70km as well. If your initial apoapsis was high enough, you'll make it to orbit before re-entry. If not, revert to launch. Efficient? Not at all, but certainly effective and simple.