If you're going to run special promotions on Halloween, make sure you go ahead and keep your customers aware at least 2-3 weeks earlier, that you're gonna have big promotions, fun gifts or good deals for them on the holiday week. Here's how by using giftcards:

Idea: about 2-3 weeks before Halloween sales, send to whoever buying on your store a special giftcard (could be value or percentage discounts, free gifts, free shipping…) which will become valid on the Halloween week (or whenever you want to run your promotion sales campaign).

Tips:

• You can design a giftcard yourself using Canva tool if your budget is too tight to hire a designer, or e-giftcard using MailChimp templates. When customers purchase on your store, attach the giftcard on the delivery package or attach the e-giftcard in receipt billing email.
• Offer giftcards of different values and promote them all widely to make customers come back regularly to collect as many giftcards as possible.

• Send automated follow-up email (suggested tool: MailBot) to remind your customers of the gift cards they have and encourage them to come back on the promotion days to redeem them.

Gift cards will encourage customers to come back to your store on the sales week to purchase, because they know beforehand they can save a lot of money if shopping with you instead of shopping somewhere else.