In Summary: Whether you adopt a flat-design style or not, interactive components must retain sufficient cues to suggest
clickability. Signaling clickability with cues such as borders, color,
size, consistency, placement, and adherence to web standards can give
interactive components the proper look.
Your designed header looks incredibly busy, it looks to me that it's been designed by marketing department throwing so many features which then makes header section very cluttered and difficult to scan.
There's good study done by NN group how to design for e-commerce websites.
Amazon: No Longer the Role Model for E-Commerce Design I would suggest looking into it.
What about "Currency" and "Language" drop downs, should I make the
NN Group also did a study on dropdowns and tracked how users interact with it. Some interesting finding came out of the study. Perhaps it's worth looking into this article do a study how often user would be interacting with it, and if it turns out to be important feature perhaps emphasis on it should be increased.
In Summary: Making users suffer a drop-down menu to enter state
abbreviations is one of many small annoyances that add up to a less
efficient, less pleasant user experience. It's worth fixing as many of
these usability irritants as you can.
Navigating the web is a means to an end and every click counts. Users need to know which areas of the page are plain static content, and which areas are clickable (or tappable).
Make clickable elements obvious to users so they don’t need to ponder the meaning of design elements or encounter nasty surprises when something doesn’t work as expected. As Jakob Nielsen puts it, “Life is too short to click on things you don’t understand.”
- While blue is still the safest link color, other colors work just as well as long as the links stand out clearly from the body text. If you don’t have a particular reason to prefer another color, we still recommend blue as the safest choice.
- The position of links can help you determine whether or not underlining is necessary. The navigation menu and lists, especially along the peripheral areas of the page, don’t require underlining. Their locations identify them as links.
- Test your color choice for hyperlinks to make sure that people who have colorblindness can spot them easily.
- Static items should not have the same color as hyperlinks.
- Don’t use blue text (or underline text) for non clickable items.
- Whatever appearance you choose for hyperlinks, make sure to apply the same treatment consistently throughout your site.