User interviews have become a popular technique for getting user feedback, mainly because they are fast and easy. Use them to learn about users’ perceptions of your design, not about its usability.
Interviews
User Interviews: How, When, and Why to Conduct Them — NN/g
The article is devoted to the issue of using various colors in user interfaces and branding design, associations and the influence of color choice on user behavior.
Colours
Color in Design: Influence on Users' Actions — Tubik Blog
Creating Empathy Maps is useful for synthesizing research data in order to better understand the users. Empathy Maps are great for creating Personas, identifying users with different mindsets.