You bought a script and it does almost what you need. Now somebody has to change it. What you hand them decides how that goes far more than who you hire.
Send the licence, not the files
Check the licence terms first. Most licences let you hire someone to modify the item for your own use, but not to redistribute the result. A developer who ends up with your files and no understanding of that is a risk to you.
Describe the outcome, not the implementation
"When an order is cancelled, the customer should get an email and the stock should go back" is a brief. "Add a function to the OrderService" is you designing badly on their behalf. They know the codebase better than you after a day.
Give them the boring context
- The exact version you are running
- Whether it is already modified, and where
- Whether you intend to take future updates from the seller
That last one changes everything about how the work should be done, and almost nobody mentions it.
Ask for it in a way you can update around
Changes in a separate file, a theme folder, or a documented hook survive an update. Changes scattered through core files mean choosing between your customisation and every future fix from the seller.
Get a note of what changed
A short list of files touched and why. In a year, when something breaks, that document is the difference between an hour and a week.
