Since I drink to enjoy the flavour, and not to get blind drunk, my comments will probably be a little less aggressively try-hard than some others I've seen here ;-P I'm going to totally disappoint on the beer front (for reasons given below) but I know me my spirits and liqueurs, so I hereby present my absolute beginner list =D
I think it's always wise to stock up slowly on a good staple liquor cabinet. Personally, I'd go for a good whiskey (variety is up to you, but a good starter is something like Johnny Walker Black Label - I'm from NZ so I know scotch better than bourbon, I'll admit), a nice gin, and a decent vodka that you can enjoy properly both in the appropriate mixes and by itself, if you so choose. If you're feeling like an adventurous entertainer (and have stocked up on buckets and carpet cleaner) you could investigate the nicer tequilas =).
Obviously, there are many more you could include, and the price will decide what/how much/what kind you feel you can get, but a decent liquor cabinet is something that everyone should have if they like drinking and entertaining.
Beer I can't comment on because I loathe the stuff (I've tried to like it, but it just tastes...used...)
Wine (if we're being broad-spectrum here) is totally a personal choice, but I always think having a nice Riesling, a decent Sauvignon Blanc and a good Shiraz and Pinot Noir covers the bases. I hate Chardonnay, so it misses out in my recommendation, but if you like it, then go ahead.
Liqueurs are a whole new world once you start looking into them, but I tend to find that, if nothing else, Chambord tends to go over big, as do Creme de cassis, Tia Maria, Amaretto, Cointreau/Curacao and Limoncello.