I just finished Deus Ex.

[WarLocke]

My idea is to build a character who is not totally a "stealthy, pacifistic type" nor totally a "hardcore, kill 'em all and let God sort em out type" -- economy of force all the way.

I played through the game this way as well. The thing you have to realize with Deus Ex, is that all weapons are deadly, whether you're trained in their use or not. You can kill with an assault rifle at Untrained just as well as you can at Master -- but at Untrained you won't be able to pull off running snap shots.

Pistols is a nice, useful skill. The weapons covered by this skill (Pistol, Stealth Pistol, Minicrossbow) will be useful throughout the entire game against everything but heavily armored targets (stuff like robots). It also allows you to effectively use trnaquilizer darts, the only way to knock someone unconscious from range (if that's a factor to you), as well as the only ranged weapon that will fire underwater.

Rifles is another good skill. All the rifle-class weapons take up 3 to 4 times the space of pistols, but they make up for it in versatility and firepower. The sniper rifle does a ton of damage, and is even effective at close range. It can also destroy cameras and turrets at Master skill level. The assault rifle has a high rate of fire (useful early on or when you're facing many enemies) and can fire explosive rounds (although they're rare until the latter half of the game). Shotguns are devastatingly effective (I'd say more dangerous than an assault rifle at under 20 feet), buckshot ammo is relatively common, and they can use SABOT rounds (armor-piercing, work great and can destroy cameras/turrets even without being Master-level).

Low-Tech is IMO, an underrated skill. Not only are they useful if you need to conserve ammo, you can sometimes destroy doors or other obstacles with them (seems to be a combination of weapon damage, skill level, and/or Combat Strength level). I haven't tried Demolitions, but it seems a little unnecessary since explosives seem to do the job just fine at Untrained. The added time to disarm explosives might be useful, though.

Computer is a skill that will save you alot of time and/or frustration if you use it. It allows you to dig up storyline info, as well as a ton of other things. For example, you might be able to bypass a camera with your Electronics skill with a multitool or two, but if you find the security terminal running it and hack it, you can just turn it off. There are also numerous security terminals that have special options, like reprogramming robots to attack your enemies. B)

Electronics is a vital skill if you want to explore everywhere (at least have it Trained), but the value lessens a bit if you also use Computer. There are enough uses for this skill that Computer can't make up for that it's still needed though, IMO.

Lockpicking is basically Electronics without the Computer caveat. Everyone should have it at least Trained.

Swimming can probably be done without, as I don't remember any plot-necessary sections that couldn't be done without it. That said though, there are alot of neat little nooks and crannies hidden in underwater areas, so training this or getting the Aqualung augmentation might be useful. You can use Rebreathers to get around either, but they aren't exactly common.

Medicine is virtually useless if you choose the Regeneration augmentation, since it's much more efficient. Otherwise, train it. :P

Environmental Protection seems useless at first, but later in the game there are alot of heated firefights and heavily-irradiated areas, so having Ballistic Armor or Hazmat Suits last longer is probably a good thing. This skill also increases the duration of Thermoptic Camo - I didn't find it of much use, but if you like it this may be a good investment.

For the record, the only skills I trained in my playthrough were Computers and Rifles (Master at end of game), Low-Tech, Electronics, Lockpicking (Advanced) and Swimming (Trained). I usually had no trouble whatsoever in sneaking around, and I could almost always handle things if I was discovered.