Update README.md

README.md

@@ -116,6 +116,13 @@ If you have found TinyGSM to be useful in your work, research or company, please
   3. Check if serial connection is working (Hardware Serial is recommended)  
      Send an ```AT``` command using [this sketch](tools/AT_Debug/AT_Debug.ino)
   4. Ensure that GSM antenna is firmly attached
+  
+If you have any issues:
+
+  1. Read the whole README (you're looking at it!)
+  2. Try running the Diagnostics sketch
+  3. Check for [**highlighted topics here**](https://github.com/vshymanskyy/TinyGSM/issues?utf8=%E2%9C%93&q=is%3Aissue+label%3A%22for+reference%22+)
+  4. If you have a question, post it in [Gitter chat](https://gitter.im/tinygsm)
 
 ## How does it work?