Thug+Safety

To help protect your shop, it is advised to hire a Thug. As time passes and you get bigger, larger level thugs will apply for the job. Check their stats and see if they'll suit your needs, don't assume that they're better just because they are a higher level.

In general though, you do want a thug as high a level as you can get.

To help improve your thugs abilities, you can perches shop upgrades(Chest/Front door/rug).