I am sure it is not the most efficient method, but it always works for me. When you have reached your desired apoapsis, I usually stop burning and wait until t- 50-30 seconds (depending on T/W) from apoapsis to burn at the horizon and create a stable orbit. You should not go down to 45 until you have an apoapsis of around 40-50 km, depending on your T/W. When you begin your turn, do not tilt further than the 60 degree mark, or halfway to the 45 degree mark. I believe the ratio between your altitude and apoapsis should be 1:3. If your rocket has a low T/W, and may be underpowered, you will need to turn later because you will not have the appropriate apoapsis. Scott Manley claims that the target altitude to begin the G turn is 10,000 m, but I believe this to be untrue. You want to have a gravity turn and gradually tilt over to the horizon line. Your angled thruster trick is a step in the right direction, but remember that the Shuttle's engines are gimballed to elevate for a flipping 10 degrees, and we can't replicate that. You absolutely do not want to begin your horizontal burn only when at your apoapsis. Another method is to build your craft with a pad TWR of 2, put some fins on the back, launch, tip over by about 5 degrees, activate SAS, wait until speed is 100m/s, tip more until you are tipped about 25 degrees, wait until speed hits MACH 1, or 330m.s then turn off SAS, release all controls and watch your craft perform a gravity turn. You either have to compensate for the thrust disbalance manually, or intsall a ridiculous amount of steering surfaces. In the end, you loose nearly all of your vertical speed, even though you're still accelerating because you just are adding more horizontal speed. You must manually tilt your rocket so that you balance altitude gain and horizontal speed gain. You add less speed to your vertical ascent and more towards horizontal so you can create that falling-so-fast-forwards-that-the-ground-moves-out-from-beneath-you effect. Not quite, a gravity turn is when you start turning over (usually east to take advantage of the planet's rotational speed) and begin moving your trajectory, like blizzy said, into a ballistic one.

Kerbal space program gravity turn flip