I want to defrag my HDD (it's at 28% fragmentation) and I want to defrag the free space to prevent future fragmentation. Should I run a regular defrag first and then defrag the free space or should I defrag the free space first and then do a regular defrag? Or does it not matter what order?
you can't really prevent future fragmentation. Windows starts fragmenting immediately after a defrag (maybe even during it). 28% fragmentation is very low (with 20% being an optimal fragmentation).
However I believe it's files then freespace but don't fully recall as i've let windows own defrag work since windows 7
with defraggler...
try the "file list" -defragmentation - relatively fast with good fragmentation-result