How can I best use an SSD?
If your main goal is to improve the performance of Photoshop and Lightroom I would focus on these specific applications. Put Photoshop files and the Lightroom lib, Photoshop and Lightroom swap/temp/history files and the Photoshop &amp; Lightroom apps themselves on the SSD.

Moving the system swap file to the SSD will only help if memory used by Photoshop or Lightroom is overflowed to the swap file. But if this is the case extra RAM would improve their performance a lot more.

Moving anything else then the files directly used by Photoshop &amp; Lightroom might result in a faster overall system, but will likely only marginally help improve the Photoshop &amp; Lightroom experience.