Here's my free advice, worth everything you pay for it. It's mostly cumulative with the advice above.
1. The start is huge in short NASTAR courses. (And this is particularly true of NASTAR courses with a flat top, then breakover--which is pretty much every NASTAR course except whatever they call Purgatory in Colorado these days.) Watch the very fastest guys on your NASTAR hill specifically on how far they skate. Get yourself some poles slightly longer than standard (perfect for powerful poling is the sizing they actually use in cross-country) and jam out of the start, but still set up clean for the first turn (without getting your feet too close together at gate clear. Falling at the first gate will shorten your race, but not in a good way.)
2. Speed suit (or jeans and underarmor--something way more aerodynamic than a bulky jacket and ski pants.) It's a full second on a NASTAR course, once your fast enough that aerodynamics make a difference.
3. The right ski, correctly prepared. For a hack, you're probably better off in a NASTAR course with a so-called "cheater" racing ski (say, 17-18 meter sidecut) rather than a currently legal GS ski or formerly legal 21 meter GS ski, and you might even be better off with a slalom ski. NASTAR resembles GS, but the courses are shorter and the course sets are tighter than a true GS. Ski with sharpened edges and correct wax for the day's conditions.
4. Ski clean. To do that, you have to fix YOUR bad habits. (Typical bad habits, depending on your handicap, include, on the slow end, dropping your hands back, frankenstein arms, skidding the end of the turns; a little more advanced, not getting forward and not weighting the outside ski enough, not committing forward on breakovers.) Fast guys have really good hand positions at gate clear, which is probably a product of doing a lot of other things right. When in doubt, work on your balance away from the gates. Couldn't hurt as long as you don't do something that does...
5. If there's a flat part at the bottom with not particularly offset gates (another typical NASTAR set) you can typically run that section in a tuck safely and with little risk.
6. Typically, your local NASTAR hill (like any other race set, although NASTAR sets are not particularly "tricky") may have a couple of areas that handling well will make a big difference--a breakover at the gate you need to turn early for, a compression as steep breaks to flat, a cranker you have to get early for two gates in advance. Get that one right.
7. Finally, if the low handicap is your end-all be all, you can game the system, if you must. Run NASTAR on a fresh cold snow day when the pacesetters ran it in cold fresh snow. After it's tracked out slightly, it'll run faster.