For melee combat you would want Assassin's Kiss (if you are sticking to a dagger) and Poison Weapon. Also in the Path of the Thief, you would want Lockpick and maybe a couple levels of Pickpocket (or keep an eye out for equipment with that bonus). If you are going to use Embrace Shadows for sneaking, Elven Stamina could be useful, otherwise it is probably unnecessary.
In the Path of Lore, Identify is handy as would be at least level 1 of Alchemy (though you can get that from a quest reward) for mixing restoration potions (higher levels would let you make poison potions, though in games started after installing the latest patch Finnigan in the Ducal inn cellar carries survivor supplies). If you are not using spells the information provided by Know Creature isn't really required. Blind could be handy, though you would have to max it to get the best effect. I tend to avoid skills like Skin of Poison, since in combat you generally want to avoid being hit too often. Curse could be very effective (level 1 can be cast multiple times quickly against an opponent), especially if you are doing poison damage, or have a weapon with an elemental damage bonus. I don't think Necroshift gets you anything you couldn't use a statuette for.
In the Path of Talents you can get 3 free levels of Trader's Tongue. Ranger Sight is much less effective than Elven Sight, so I'd try to rely on equipment bonuses for sight boosts. Wisdom would give you an extra character level. I don't know how effective Charm is, but nobody has raved about it in the forum that I recall. Magic Barrier and Survivor's Instinct would both be helpful. Aura of Command wouldn't be useful if you are not using traps or summoning. Some people like Heaven's Gift, but as the game progresses gold is easier to come by so its benefits are limited.