Repair it or replace it
Screens and batteries are usually worth fixing. Most other failures on an older device are not.
What's usually going on
A cracked screen or a tired battery is a routine repair. Liquid damage, a failed main board, or a device too old to receive security updates usually is not worth the money. The age of the device matters more than the cost of the repair.
Worth trying first
Check the age and the updates.
If the device no longer receives software updates from its maker, replacing it is the safer choice, whatever is wrong with it.
Check the warranty.
Look up the serial number on the maker's website, and check for AppleCare or any coverage from the card you bought it with.
Get the maker's price first.
Apple and the major manufacturers publish prices for screens and batteries. It is the number to compare any other quote against.
Back up before any repair.
Repair shops often erase or replace devices. Assume it will come back empty, and confirm your backup opens before you hand it over.
Sign out if you are replacing it.
Before trading in or recycling, sign out of your accounts and erase the device.
When to hand it over
If you'd rather have a straight answer on whether it's worth fixing, or would like the new device set up with everything moved across.
Your own technologist, on call.
Tell us a little about your setup. We'll take it from there.