diff --git a/README.md b/README.md
index b4d5dfe..d81da22 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,14 @@ Goc can collect code coverages at runtime for your long-run golang applications.
     ...   
     ```
 
+## Tips
+
+1. To understand the execution details of goc tool, you can use the `--debug` flag. Also we appreciate if you can provide such logs when submitting a bug to us.
+
+2. By default, the covered service will listen a random port in order to communicate with the goc server. this may not be suitable in [docker](https://docs.docker.com/engine/reference/commandline/run/#publish-or-expose-port--p---expose) or [kubernetes](https://kubernetes.io/docs/concepts/services-networking/service/#defining-a-service) environment since the port must be exposed explicitly in order to be accessible by others in such environment. For this kind of scenario, you can use `--agentport` flag to specific a fixed port when calling `goc build` or `goc install`.
+
+3. To use a remote goc server, you can use `--center` flag to compile the target service with `goc build` or `goc install` command.
+
 ## RoadMap
 - [x] Support code coverage collection for system testing.
 - [x] Support code coverage counters clear for the services under test at runtime.
diff --git a/cmd/commonflags.go b/cmd/commonflags.go
index e48f7c9..c12d70e 100644
--- a/cmd/commonflags.go
+++ b/cmd/commonflags.go
@@ -27,7 +27,7 @@ func addBasicFlags(cmdset *pflag.FlagSet) {
 func addCommonFlags(cmdset *pflag.FlagSet) {
 	addBasicFlags(cmdset)
 	cmdset.StringVar(&mode, "mode", "count", "coverage mode: set, count, atomic")
-	cmdset.StringVar(&agentPort, "agentport", "", "specify fixed port for registered service communicate with goc server. if not provided, using a random port")
+	cmdset.StringVar(&agentPort, "agentport", "", "specify fixed port for registered service communicate with goc server. if not provided, using a random one")
 	cmdset.StringVar(&buildFlags, "buildflags", "", "specify the build flags")
 	// bind to viper
 	viper.BindPFlags(cmdset)