Check intent before blaming the store
First confirm the traffic is qualified. Traffic from a broad interest audience or a viral video behaves nothing like traffic from a high-intent search query.
Segment your analytics by source and compare conversion rates. If one source converts and another doesn't, the store is fine and the targeting isn't.
Then follow the drop-off
Look at the funnel step by step: sessions, product page views, add to cart, reached checkout, purchased. The largest percentage drop between two steps is your priority.
A drop between product view and add to cart is a persuasion problem. A drop between checkout and purchase is a friction, cost or trust problem.
Fix the biggest leak first
Resist the urge to change everything. One measurable fix at the largest leak will teach you more than ten simultaneous changes.