Update readme doc howto troubleshoot (#1052)

Note common troubleshooting tools/steps in README

README.md

@@ -54,6 +54,7 @@ can help a lot :-)
 - [Box Format](#box-format)
 - [Create Box](#create-box)
 - [Package Box from VM](#package-box-from-vm)
+- [Troubleshooting VMs](#troubleshooting-vms)
 - [Development](#development)
 - [Contributing](#contributing)
 
@@ -1453,6 +1454,43 @@ $ export VAGRANT_LIBVIRT_VIRT_SYSPREP_OPERATIONS="defaults,-ssh-userdir,-ssh-hos
 $ vagrant package
 ```
 
+## Troubleshooting VMs
+
+The first step for troubleshooting a VM image that appears to not boot correctly,
+or hangs waiting to get an IP, is to check it with a VNC viewer. A key thing
+to remember is that if the VM doesn't get an IP, then vagrant can't communicate
+with it to configure anything, so a problem at this stage is likely to come from 
+the VM, but we'll outline the tools and common problems to help you troubleshoot
+that.
+
+By default, when you create a new VM, a vnc server will listen on `127.0.0.1` on
+port `TCP5900`. If you connect with a vnc viewer you can see the boot process. If
+your VM isn't listening on `5900` by default, you can use `virsh dumpxml` to find
+out which port it's listening on, or can configure it with `graphics_port` and
+`graphics_ip` (see 'Domain Specific Options' above).
+
+Note: Connecting with the console (`virsh console`) requires additional config,
+so some VMs may not show anything on the console at all, instead displaying it in
+the VNC console. The issue with the text console is that you also need to build the 
+image used to tell the kernel to output to the console during boot, and typically 
+most do not have this built in.
+
+Problems we've seen in the past include:
+- Forgetting to remove `/etc/udev/rules.d/70-persistent-net.rules` before packaging
+the VM
+- VMs expecting a specific disk device to be connected
+
+If you're still confused, check the Github Issues for this repo for anything that
+looks similar to your problem.
+
+[Github Issue #1032](https://github.com/vagrant-libvirt/vagrant-libvirt/issues/1032) 
+contains some historical troubleshooting for VMs that appeared
+to hang. 
+
+Did you hit a problem that you'd like to note here to save time in the future?
+Please do!
+
+
 ## Development
 
 To work on the `vagrant-libvirt` plugin, clone this repository out, and use