Since you’ve already mastered the basic languages of web development (HTML, CSS, JS), you are now basically skilled as a Front-end Designer.
Now, how to be a skilled UI Designer?
- Learn how to interpret the Product Requirement Document
- Learn how to translate the Task Flow Diagram into individual Wireframes and eventually into an Interaction Diagram
- Learn how to transition the designs to the Visual Designer and Front-end Designer/Developer
It’s important to establish the role of a UI Designer in the context of the Design Process.
Based on the Elements of UX by Jesse James Garrett (personally modified), these are the 5 planes:
- Strategy: Business Objectives, User Objectives
- Scope: Features, Requirements
- Structure: Information Architecture, Interaction Design
- Skeleton: Information Design, User Interface Design, Navigation Design
- Surface: Sensory Design, Visual Design, Accessibility
You could use this as a guide for the Design Process because the planes build on top of the other-as in a process. UI Design is in one plane and there are 4 other planes to consider.
This could also serve as a guide for the topics to further your knowledge.