To summarise/add, these may help, in no particular order:
1. Hydrate
2. Dive deep incrementally
3. Descend slowly
4. Gain experience at depth
5. Reduce workload
6. Reduce task loading
7. Know your equipment
8. Be aware you're narc'd
9. Have a good buddy
11. Remember how to count
IMHO, it's a matter of how badly you get it and how you deal with it
Good enough list.
what I'll add to that is to learn how to breathe properly so you're not inadvertently making it worse by CO2 retention. IIRC Brett Gilliam once wrote an article in which he described his breathing technique for the 300ft air dives he did.
Narcosis is something you need to understand on a couple of levels. First just on the physical level (you get slower, you feel drunk, you lose concentration) but also on the psychological level... meaning what it does to *you*; how it makes you feel.
I've made a lot of deep dives and I have a very good idea of what to expect and what things I can and should not do deeper than about 36 metres. For example, deeper than 36 metres I simply can't concentrate well enough on most days to go inside a wreck except on the simpelest of penetrations (swim throughs). There's no really good way to get that experience without just making the dives.
Proceed slowly, ask your buddy for input and be completely honest with yourself. I don't think you can really *manage* the narcosis but you do have some control over your own psyche and therefore you can *manage* the reaction to it to some degree.
R..