There's loads of general system stuff to tweak for space, hibernation file is one of them (if you never use it, there's no sense having a hiberfile the size of your ram). Pagefile can be reduced to 1.5GB if you have 4~8gb of ram usually, turn off system restore, turn off indexing, turn off superfetch etc.
There's loads of stuff you can do to help with space, but it's not all related directly to SSD's they only start to slow down above 85% usage really..