I have only been doing the SE gig for three years now and I have learned a lot from my own mistakes or from other SEs I work with. Here’s a compilation of things that I regard as being the “trade-craft” for Sales Engineers:
Laptop: Your company will probably outfit you with your own laptopwith enough juice to run a VMWare demo and PowerPoint slide deck simultaneously, while projecting your desktop onto a presentation screen. Make sure you do the regular maintenance so your system will keep up with the demands. There’s nothing more frustrating than being in the middle of a 3 hour demo and your system freezes for no reason and you have to reboot, thus delaying the demo and creating a 10 minute window when the customer loses interest in what you are presenting. Additionally, if your company allows you to claim business related expenses, drop the cash on a solid-state drive for your demo VMs and install the maximum amount of RAM your laptop can handle.