Thank you so much for mentioning our business relationship in your post, I really appreciate it. At the moment, I must admit to feeling a bit humbled. It has really been a great pleasure working with you over the years.
I'd also like to add that in my experience it is vital to make sure that there is a plan understood by all parties and who is responsible for what. Many times (especially with servers that have been in place for a long time), things just kind-of grow in strange ways. For example, maybe that last administrator created a separate MySQL installation - or is using Postgres for some specialized purpose. Missing things like that by not double, triple, even 10x reviewing the plan can have bad consequences. And definitely understand what your actual needs are - there is a big difference between a $29/month shared server, $75/month VPS server, or a $175/month dedicated server. Some web hosting companies will low-ball the server and then charge you for support, others (like us) think this is just part of what being in this business is about and keeping customers. I'm not going to make a judgement one way or the other, I know what works for us, my point is to just know what you are getting - the fewer surprises the better.
In other cases, you may not have control over things like DNS servers - or even direct access to the MySQL files (requiring a dump/load), so its really important to not only know what has to be done -- but how it has to be done. Even if the migration is as simple as pressing a button, its important to know who is pressing it and when. :)
Also, I like to keep the old server around for a while (a month or so) just to make sure that nothing was missed and get some sort of backup of it - even if its just creating an archive file of the important directories. Of course, backups are a subject in its own right - and adding a database to the mix can greatly complicate it. One of my favorite quotes is: "The backups are fine, its the restores that aren't working....."... But, no matter what: get a backup of that old server. One of our prominent clients lost everything at their old hosting company and all they had were the mockups/images from their web designer - it took almost a year to rebuild their site back in 2000 - and they still aren't back to the same traffic levels they were before this happened. As you know, I won't install a server without some sort of redundant disk system (mirroring, RAID, etc), but this is only part of the equation. If you can't build out a new server from your backups, then your backups are probably insufficient.
Thank you again!
Senior Systems Integrator
gregs (at) net-virtual.com