Locate the centre of the crown once you have your top anchor and always keep that centre in mind your mind (keep on reverting back to its position as you move around the crown later on in the job).
Then look around the top section and spend some time deciding a good height where theres lots of side laterals roughly/at least 1/3 in diameter of the proposed pruning cut to prune back to. Remember this is important as the pruned branches have a better chance of survival if you do this and you want to avoid stub cuts as much possible.
Once you have a rough height to work to always try and get above that cut line its sooo much easier to be cutting below your head than above it. So good anchor point is key.
When cutting the top remember its only the very middle that is the highest bit so start a gradual slope down as you meet the sides of the crown.
Once at the side try and distinguish on the lowest limbs on the tree a suitable reduction point to aim for.
Imagine a curverd line joining the already pruned top section down to that lowest limb reduction point that you have chosen. Prune down the sides to that lowest limb. Work around the sides to complete a quadrant that is visible to your groundie so that he/she can see easily wether your cuts are in/out also completeing a quadrant as close to your chipper will also allow you chuck to prunings more easily out the crown and improve overall job efficiency.
Sometimes I start my quadrant around the back of the tree so once I get my eye in I know the money shot (generally the side that will get the most visual profile) will be looking its best.
Once you have a completed quadrant section just keep on goin around the sides..it should get easier at this point to see the shape.
I always take a decent set of poles with me to cut anything upto 20 feet in height. This saves a bit of time and fatigue and its easier to see the shape from the ground.
Try your hardest to get right out on those limbs. The best reults come from those who get right out into the tips. Be flexible, patient, always look up, down and around - im constantly trying to map that 3d dome in my head....I quite often draw imaginery lines with my hand to try and match up the shape of the dome...must look pretty wierd to onlookers...a spaced out tree hugger doing tai chi in the trees....but it really helps me and I havent been sectioned yet!