Understand that people DO JUDGE books by their covers. Your social media branding is either ADDING TO or HINDERING your credibility.
To have a crystal clear Twitter Header image make sure you are designing for 3000 X 1000 pixels. This will allow your image to be crystal clear.
Also design your Twitter Profile image to be 500 X 500 pixels.
Think of this space as a virtual billboard. How can you use this virtual real estate to position you as the expert, how can you use it to promote your lead magnet and your list building efforts.