How can I scoop fuel without getting cooked?
Solution 1:
One important thing to remember is that heat doesn't cause damage until around 140% heat, so you have plenty of range to play around in.
v 1.2 Update: The new heat mechanic in 1.2 has moved the heat goalposts around, meaning you now start taking damage to modules at 100% heat[1] and damage to your hull at 140% (or the second line on the new heat bar).
[1] - The point at which you hit 100% in 1.2 is the same point you would have hit ~140% in previous versions, so you are not at a higher risk, it's the measurement that makes more sense.
Video Guide
The video guide is still relevant in 1.2 and higher, just bear in mind the above about the heat numbers. i.e. don't go above 100% any more.
How I've always done it
The way I usually fill up my tank is to aim first, have the star just on the edge of your view then throttle down to zero. When in supercruise this does not mean stationary so adjust your angle in small increments so that your heat stops rising but you are still getting a decent rate. If you are in a hurry, adjust your speed up in small increments as well which will give you a better rate but increase your heat, so you have to keep watching.
When scooping a lot of fuel, there's not much you can do about it other than find a good angle then go read reddit whilst you scoop.
Rate vs Scoop size
Each size and class of scoop will have a different rate and finding the optimal for your currently fitted scoop will take some experimentation. As above, until you know what a "safe" rate for your scoop is, just slowly increase the rate by adjusting your speed or angle against the star until your heat stabilises at a value less than 100%.
Solution 2:
Don't touch the brake. Stay at 0.3c. Fly close to the line (that goes round the star). If you cross the line you'll drop out of supercruise. As you are scooping move around the star and line up your next destination. If you start to overheat don't touch the brake, just move slightly away from the star and it should stop rising. Non-the-less you will be able to achieve 100% refuel rate. This is the fastest and most exhilarating method - if you don't believe me then try it. I'm going to make a video of this because the other methods are slightly inferior.
Solution 3:
All internal modules produce heat when enabled. Before scooping just open the ship menu ('4' by default) and disable modules that are not used.
Shield is a top candidate to be disabled or uninstalled as it doesn't work in supercruise anyway and produces a lot of heat. Keep in mind that it won't re-charge instantly so crowded system isn't a good place to scoop.
Generally, quick overheat is a sign that your ship configuration doesn't fit for long travels. High heat productions means high energy consumption, heavy modules and generator.