If you are struggling, the best thing to do is reach out to the CiviCRM community.
If you cannot find the answer in this guide or by searching in the CiviCRM StackExchange site then please ask. Asking questions on StackExchange not only helps you but may well help others who follow you.
That said, this is a small list of some of the commoner problems extension writers encounter.
Extension not doing anything¶
Q: I've created the files and edited them but I don't see the expected changes.
A: Did you install and enable your extension? (<site>/civicrm/admin/extensions?reset=1)
Civix error messages¶
Q: I get Error: "Cannot instantiate API client -- please set connection options in parameters.yml"
A: You might have missed the step about setting 'civicrm_api3_conf_path' (https://github.com/totten/civix/), or it didn't get set properly for some reason.
Q: I've tried to generate a page/report/search/upgrader/etc with civix but it's not working.
A: For all of the various types, you must first run generate:module, and then `cd` into the folder (e.g. com.example.myextension) before running one of the other `generate:` commands.