Some of this is probably a bit obvious, in which case I apologize:
Try to print off/copy a few of the sheets that have the tables most typically used in BT for easy reference.
Try to make sure new players have 'Mechs that are substantially more awesome than yours, then ensure they get to beat the snot out of you. Show them the true horrors of BT in self-depreciating manner. IE, one match I did last week was an Atlas vs. a Cyclops. Another was a Zeus vs. an Awesome (Bit more evenly matched) but that included several turns of the Awesome being shut down due to heat and other shenanigans.
I'd even suggest changing dice results to ensure certain things happen so they can see it, IE, piloting checks fail when they would otherwise succeed, same for shutdown rolls, or critical checks. Naturally with yourself as the victim.
And make sure to get some physical attacks in. They are awesome, and must be shared.
Last piece: try to make sure they don't feel overwhelmed by the # of rules. Make sure they realize that you only have to take on no more rules than you want to deal with, if you've taught them the box set rules, they know 90% of what the game has to offer.
Along those lines, if you know the answer to something that can be found on the tables, just give them that info. The less time spent digging through tables, the better. They can memorize them whenever they want.
Paul