sound proofing in joists in flat

Here's a weird one for you... Some time ago a study was done and it was found that the cardboard egg trays were better and cheaper than most other things as the cardboard is soft which slows the sound down and therefore reduces the volume, the shape reflects and refracts sound vibrations adding to the effect and when two layers were done with an inch or two between them it was even more effective. You could consider soundproofing foam, simply google or eBay for it. It's not tricky to do, but a spare pair of hands helps to hold things in place and pass things to you as you might be spending a long time on steps and reaching into the air which is uncomfortable after a while, so less stepping up and down is very helpful.