You might prefer to fry the aubergines, rather than to bake them, for a moussaka. In which case, you might be tempted to salt them first -- not because they are bitter, but because according to some writers they will absorb less oil if treated in that way. Salting is not necessary. Treat the aubergines as you would if you were baking them, by brushing them with oil. Lay them in a heavy-bottomed pan, over a low-to-medium heat, and season them. As they cook, they will of course lose the moisture that an initial salting was intended to remove. In other words, you get the same result.
Browning mince is another procedure about which most cookbooks are misleading. The process takes a long time if you throw 400g of mince into a pan and stir it around: first, the mince throws off its moisture, in which it stews; eventually, the moisture evaporates, and the mince starts to brown; bits of the mince start catching on the pan. If I want to brown mince (perhaps for shepherd's pie), I form it into patties, which I flash-fry or place on a hot grill pan. For the stews in spaghetti Bolognese or moussaka, I don't bother -- and I am not sure that I notice the difference. (More about this subject here.)