You can generally outpace a troll at a light jog, so i find a bow, arrows (preferably fire), 2 health foods and a stamina food are perfectly fine for taking on trolls. The 2 health foods will usually mean you can take a hit if you do make a mistake (but rarely can you take two if you are still in newb gear) and the stamina food means that you can still hop over obstacles or sprint for a little when the troll does get a bit too close for comfort. Fire arrows are often good because they will burn roughly long enough to take potshots, as in take a shot and jog for a little, and about the time the troll stops to take a swing and a miss at you it's about time to apply more fire as well.

As for skills, don't worry about it much. If anything, trolls are great for training your bow skill since you might not be the most accurate at the low level bow skils but that doesn't matter much when aiming at such a large enemy. "close enough" still hits it just fine. Plus they will take a decent amount of shots so you get ample opportunity to raise that skill in the process. The main concern is everything else joining in while you try to focus on the troll. Avoid greydwarf nests, dungeons or towers where skeletons tend to spawn (perhaps even the starred ones if unlucky), or fighting at night when everything spawns even more often. Depending on your approach you might even prefer to lure the troll into an open meadow with weaker enemies less likely to swarm you, but inversely the terrain and trees in a black forest can also help slow down the troll if you are already fine with navigating those same obstacles yourself (plus you can use the troll to break some of it, like fine wood or ores) for your own benefit.