Well there are a couple of things.
1. A lot of the time after downloading the guest agent zip from the server they forget to right click on the zip file go to properties and click "Unblock" on the file. If you don't do that and you go straight to unzipping the agent the scripts won't run because windows thinks they are untrusted.
2. Static IP is fine as long as all the proper information is getting entered for the network config during the customization process so it can reach the IaaS server. The agent must be able to talk to the management server during provisioning.
3. You would be surprised but many people forget to put the custom property in the blueprint to actually make it use the guest agent. Make sure the blueprint has the custom property of VirtualMachine.Admin.UseGuestAgent and value of true
4. You can always institute a delay, which is recommended, between the customization and the guest agent config. You do this by using the custom property VirtualMachine.Admin.CustomizeGuestOSDelay and put 1 minute of wait time in, which is expressed as 00:01:00 for the value.
Hope this helps
