diff --git a/README.md b/README.md
index 65622b7593cbd77085616a687e2a37db5f2a16b3..22c7c10f3e96c7b7e63c87e1291de5ba063176bb 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,19 @@ For a complete build from scratch of the VTP VM image:
 ~~~
 # download packer_x.x.x_linux_amd64.zip from https://www.packer.io/downloads.html
 unzip packer_x.x.x_linux_amd64.zip
-./packer build -only=qemu -var headless=true packer_files/vtp.json
+# cd /path/to/where/you/want/packer/ && unzip ~/packer_x.x.x_linux_amd64.zip
+
+# Check the parameters in packer_files/vtp.json, especially:
+
+      "qemuargs": [
+        [ "-m", "1024M" ]
+      ],
+
+... as 1G is probably not enough to build a typical NMM platforn.
+
+Once you're ready:
+
+sudo /path/to/where/you/unpacked/packer build -only=qemu -var headless=true packer_files/vtp.json
 ~~~
 
 If you are inside the VTP environment and want to re-run a playbook:
@@ -15,6 +27,19 @@ cd /root/vtp/ansible
 ansible-playbook -i hosts <playbook>.yml
 ~~~
 
+# Assumptions
+
+It's assumed, at this stage, that the environment you're building on
+is a 14.04/16.04 physical host configured as per workshop-kit/ansible,
+including:
+
+- br-lan is up and running
+- dhcpd is up and running
+
+Note: if you already have VMs/containers running on the physical node,
+be aware that the VTP VM's own containers will be attached to br-lan
+on the *physical* node, and thus may conflict with each other at IP level).
+
 # Overview
 
 The VTP virtual machine is built using a scripted install process. This