SSD Windows 7 SP1 best practice?

I want to make a 25Gb partition for my OS (I am currently using this size on HD and its not hitting the limit). I have heard that u should leave unallocated space after a partition on an SSD, is this accurate? I could place my temporary directory on the 2nd partition of the SSD and any programs or games to use the rest of the 128Gb SSD. Is there a directory/file that is written to alot which I should avoid putting on the SSD to preserve its lifespan?

I’ve done a little googling but it presented more options rather than directions and I need to decide how I will partition before I fit my upgraded parts. Once I am on my updated rig I can go about looking for the best tweaks.

My main query is whether I should leave unallocated space after each partition.

No, not after each partion, but maybe it is useful to leave at least ca. 10% of the available SSD space unallocated. This is not really needed for some SSDs, because some SSD manufacturers have already reserved some extra "overprovisioning" space, which you do not see from within the Disk Management.
By the way: I do not recommend to install any Windows OS onto a 25 GB partition of a 128 GB sized SSD. Such small sized system drive partition may be good for a HDD, but not for an SSD. If I were you, I would create a ca. 110 GB partition for the OS installation and add a HDD for the storage of data (and for a periodical backup of the system drive).