There is nothing more irritating than a weak or bad signal of mobile network. I have listed some points which will help you to overcome this problem.
1. Turn off your mobile signal off and on again
This is a tried and tested method which works most of the time. If there is no other cause than power cycling your phone may fix it on its own by simply switching the network on or off. You can also use the Airplane mode to switch off the signals.
2. Charge your phone to get proper signals
Sometimes due to less battery power your mobile phone may go into some type of power saving mode and will transfer less power to mobile signals so it is always best to charge your battery to get optimum mobile signals.
3. Change your location
Sometimes by just changing the way you hold your mobile can solve the signal issue. Maybe you are holding mobile phone in a way so that the antenna is covered and signals reception becomes weak so try to change the grip of holding the phone and move a bit and check if this solution helps you or not.
4. Change your Mobile
If you are consistently getting signal issue no matter where you are then there is some issue in your mobile phone antenna and your mobile could be the problem.
5. Change the service provider
Even after changing the mobile handset signal problem persists than change your mobile carrier because maybe there is an issue with the mobile carrier in your area and due to the patchy network you are facing signal issue.