Start with the changes that remove friction, since they’re cheap and quick to test. In rough order of impact:
Cut unnecessary fields: every extra field costs conversions. Remove company name, second address lines, and anything you don’t need to fulfill the order.
Enable guest checkout: forced account creation is one of the most common reasons shoppers leave.
Show the full cost early: unexpected shipping or tax at the last step is a top cause of drop-off, so surface it on the cart page.
Offer the payment methods your customers use: local options, wallets, and UPI or card choices depending on your market, so people don’t abandon because their method is missing.
Fix mobile first: check button size, keyboard types on form fields (numeric for phone and card), and load speed on a mid-range phone.
Add trust cues near the pay button: security badges, a visible return policy, and contact details.
Test one change at a time: otherwise you won’t know what moved the numbers.