Carmen Sol's headline offer is the Labor Day Sale with 20% off sitewide, which applies to everything you're buying. This deal suits shoppers looking for the deepest discount across the brand's full range, and it beats the other percentage offers if you have any size basket to spend.
For smaller baskets under $150, the Labor Day Sale's 20% off sitewide is your best bet. If you're a first time customer and want to stack a little extra savings on top, you can also sign up to the newsletter to get 10% off your order—but since 20% beats 10%, the Labor Day Sale is the stronger option either way.
For orders of $150 or more, you still want the Labor Day Sale's 20% off sitewide. Free shipping on orders over $150 is a nice perk if you hit that threshold, but the percentage discount on your full basket will save you more money than the shipping waiver alone.
If you're buying primarily from the sales section, check whether the up to 50% off sales styles deal applies to what you're after. On heavily discounted items, the percentage off those sale prices could exceed the Labor Day Sale's 20%, so it's worth comparing at checkout if most of your basket is already marked down.
Since only one offer applies at checkout, add your items to the basket and compare the final totals. Apply whichever discount produces the larger saving—you'll see the difference when you enter or apply the relevant deal.