doc: add tips section in README

README.md

@@ -89,3 +89,19 @@ This will result in the following output:
 For more details about the output customization see the configuration options of the `zlog` module. Following options are available:
 
 - _timestamp_ (default: `true`): Prepend the current timestamp before each log message.
+
+## Tips
+
+The following list shows some tips on how to use logging more effectively. These tips do not apply just to `zlog` (and not even only to zig code).
+
+- Use `errdefer` to directly print messages on failures in the same function they occur:
+  ```zig
+  // assume log is already defined before (with the corresponding scope)
+  const port = port: {
+    errdefer |err| log.err("failed to read the port number: {}", .{err});
+
+    var buf: [fmt.count("{}\n", .{maxInt(u16)})]u8 = undefined;
+    const len = try process.stdout.?.readAll(&buf);
+    break :port try fmt.parseInt(u16, buf[0 .. len -| 1], 10);
+  };
+  ```