GlassesShop currently lists the Get your first pair free voucher at the top of the page, and that is the lead offer here. Use the first pair free code if you are a new customer who wants one complete pair with no outlay, because the code makes that pair free; note the terms say it cannot be used with any other offers. This offer is best for a first time purchase where you only need one pair.
Very large orders and frames heavy baskets. If you plan to buy many frames or expensive frames, the 50% off first order and the 50% off all frames and free shipping codes normally save the most money on frames. For example, on a $300 order made up entirely of frames, the 50% off code takes 50% off (percent 50%), leaving $150, so you save $150. The $100 off code that requires over $259 is an alternative on mixed orders; a $300 mixed order using the $100 off code leaves $200, a $100 saving, which is less than the 50% frames saving when the whole spend is on frames.
Complete eyewear packages (frames plus lenses). Use the 40% off full eyewear packages code when you are buying frames with lenses included. On a $120 complete eyewear package, the 40% off discount (percent 40%) reduces the price to $72, so you save $48. That will beat a fixed amount coupon such as $15 or $35 at this spend level when the discount applies to the items you are buying.
Orders that just reach the flat dollar thresholds. If your cart is small but meets the fixed thresholds, pick the matching dollar off code. For $59 to $108 choose the $15 off over $59 code; on a $80 order that code takes $15 off, leaving $65. For $109 to $258 the $35 off at $109 minimum is the right pick; on a $150 order the $35 saving leaves $115. For $260 and up the $100 off on orders over $259 is the best flat rate option for mixed carts if percentage codes do not apply to your items.
Buy one get one and sunglasses and sale items. If you want two pairs with lenses, the buy one get one free code applies when you add two eligible items and will often beat percentage codes on the same items, because the second pair becomes free. For sunglasses choose the 25% off entire order sunglasses code when your purchase is sunglasses only. If the items you want are marked in the sale, the up to 80% off clearance price can be the biggest saving for those selected styles; sale items may be excluded from codes and the sale applies only to selected styles.
When choosing between the options that apply to your basket, calculate the final total under each code and take the one with the lower total. Remember the first pair free voucher cannot be combined with other offers, and most codes are new customer only or limited to specific categories, so pick the single code that yields the lowest final price for the items in your cart.