Prep

Review the 9.0 Release Notes
Do you have custom reports or forms? If so, please consider installing a test version of 9.0 to confirm they will work with 9.0 and its many database changes. If there are any issues, please contact NewHaven Software Support to contract any necessary fixes.
Do you have custom integrations? NewHaven will keep all standard integrations current including those with UPS, FedEx, Endicia, Peachtree, and payment gateways. If you have developed any integrations of your own, please consider installing a test version of 9.0 to confirm they will continue to work. Please contact NewHaven Support if you'd like assistance with setting up or updating your test environment.
Fulfill all pending catalog requests
Download the 9.0 update and get your v9 release code from Support Downloads

Install

Get everyone out of CMS (TIP: delete the file CMSNET.dat to confirm all users are logged out)
Update your server - This process should take ~10 min when upgrading from 8.0. It will take much longer for upgrades from 7.0. Upgrades from versions earlier than 7.x are not supported and, in such cases, an intermediate update to 8.0 will be necessary.
1. Verify you can log into CMS without error
Update workstations (required if updating from v7, optional for v8 but recommended to update Help file)
1. Update Help - If not performing workstation updates, you should instead copy the file CMS.chm to all workstations' \NewHaven Software directory from \NewHaven Software on your server

Tell CMS which of your catalogs are active if you have more than one defined (all are marked as active during the 9.0 upgrade and you may want to make some inactive so users cannot select them when entering a catalog request)
If you import catalog requests, you'll need to tell CMS which of your catalogs to associate with each import order source - Setup>Fulfillment>Import Sources and Plug-Ins>Import Options

Arrival Dates and Cheapest - http://screencast.com/t/neoCUVPEeE
Package Exceptions - If you have shipping methods that you use but do not want CMS to offer as a suggested shipping method (when the method you've selected is invalid for the destination/date), you may check the "Exclude from Cheapest" checkbox on any such shipping methods. CMS is looking for the cheapest alternative when the method you've selected is not appropriate for the ship-to address (or arrival date) so choosing this option will keep CMS from its cost comparisons - http://screencast.com/t/4EQwfO0RrVr
S&H applied per recipient - http://screencast.com/t/yQy3y4vMdlF
Remove prompt from label processing in Manifest - http://screencast.com/t/N7ZQHBPGL
Add print task 481 to shipment confirmation email in place of task 480 - Example: http://screencast.com/t/mczAmACLDEvE
Configure what non-shipping days you have (at least check the boxes for Sat and Sun) - http://screencast.com/t/Faisw8nPW
Update Zonedays data to change CMS defaults if/when desired - http://screencast.com/t/dmGefU0Q6w8Z