Designing w/ a grid adds order to the chaos that the creative process often brings. Using a grid is easy in Illustrator or InDesign. Both apps allow the user to save and import a grid as a template. Photoshop doesn't have the same function. The best alternative is to create paths/convert to lines using brush tool/ then save and place that grid as a template into a new doc.
1. Blank PSD doc
3. Path tool converted to stroke ( 2 pt width)
4. grid placed in PSD doc with images
5. images layout using grid
A grid can be the calm that the creative storm needs. Adding structure and stability making a page feel clean and easy to read.