Are you familiar with the basics and fundamentals If not , Don't rush, take your time and learn, be familiar with certain things before climbing into stores. If you are trying to card UK stores, get a clean residential proxy which will match the card holder zip, setup your machine properly(clean residential proxy matching the card holder's zip, warmup the shop)
Note: You can't just get a card and start shopping gift cards. You should know the type of Anti-Fraud system implemented in the store and what type of information they need to bypass such Anti-Fraud. etc. (Sometimes you can fail a few times before succeeding).
But the goal is to succeed. So be familiar with as much Information before trying to card.
Hope this helps for now.