Unless you find it very difficult to avoid impulse buys, then your credit cards are best kept in your wallet rather than a drawer in the kitchen, a cookie jar or even a home safe. Keeping them loose in your pocket or bag is not recommended though. They might fall out and are very easy for pickpockets to remove.
The main reason a wallet is the safest place to store your cards is because you will know instantly when it has been stolen and can immediately cancel the cards. Leave them at home and thieves will have several hours to play with them before you are likely to even notice. There is also a small chance that the police will be able to use the cards to track that handbag snatcher, pickpocket, or worst of all muggers, if the no-goods are foolish enough to try and use them.
Generally speaking, it is more likely your house will be broken into than you will be personally robbed. This is especially so if you take care, keeping a hold of your bag at all times and not sticking a wallet in your back pocket.
Opportunistic thieves are not usually professionals. Housebreakers often are. Credit cards left at home along with a host of identifying information and possibly even pin numbers are an utter gold mine for a burglar who knows what he is doing. Your credit score could be completely ruined within half an hour. However a bag thief probably won’t even try to use the cards. If he does it just makes it rather easy for the police to catch up with him.
Then you have the not-exactly-thieves who could also cause problems. These are also known as children. Leave your credit card at home and your children will know where it is. At some point they will also be tempted to use it, perhaps even with the intention of paying you back. This could push you over your limit and affect your credit score, especially if you never found out until your statement came through.
Flatmates, other relatives, and even partners might also use your card for a whole range of reasons, some perfectly valid such as paying off an unexpected bill. However it is best if you take control of your own finances by not leaving temptation lying around.
If carrying a credit card makes it impossible for you to resist buying things you cannot afford then it is probably best you don’t have one. Carry a debit card instead, and pay off any credit cards. If you think you need one for emergencies but do not wish to carry it then find a very secure hiding place and make sure only those you really trust know where it is.