Here is a short check list of mine about what a designer of a self service portal should care about before hand over the design:

1. WCAG 2.1 AA level. (Pro tip: Install WebAIM extension for Chrome).

2. 12-grid layout, possibly.

3. 8pt baseline grid.

4. All pages must have a header, a content area and a footer

5. Left-handed one-column layout is recommended.

6. Buttons should be left-aligned

7. Primary button is always on the left.

8. Use icons follow 8pt grid and scale well.

9. Keep the design light and airy with lots of white space

10. Divide the self-service solution into small steps