Hi Mange,
Totally agreed - lowering the level into the lossy encoder is going to help,and always upload lossless if Soundcloud, or any other digital distributor, is doing the encode. I'm not sure that I agree with narrowing the super highs - I haven't seen the to be a useful strategy at this point.
To add to that, if the digital distributor will accept 24 bit files be sure to provide them. I have found that encoding from 24 bit yields a better result every time. My hope is that all digital distributors will accept 24 bit in the future. Unfortunately that is not the case at the moment.
Best,
Adam