You’ve got 4 trees that can be used to deal damage - the 3 combat trees and War Cry on the left War Cries tree. The most common builds are Whirlwind, Berserk, Frenzy and Singer, then Concentrate and Double Throw.
Because of your connection issues Trav is very dangerous. You’ll need to be hyper sensitive, intuitive of your connection quality.
What I recommend is you figure out which main attack skill you enjoy playing the most and practice it, get fairly efficient with the skill. A barb can kill everything in the game if playing main WW/Zerk or main Frenzy/Zerk.
I also suggest you choose your weapon class from the start. Max out whatever weapon mastery you’ve chosen right off the hop, so when you reach clvl 20 you have a weapon mastery maxed and one on Bash, and one on Double Swing if going Frenzy. From there max BO, put one on Berserk, then Max your main attack skill. If going WW you’ll be fine in normal and nightmare with only 1 point on it - it still crushes. Good starter weapons that are easy to make are rune words Steel, Malice, Strength, Holy Thunder, Honor, King’s Grace, Passion, Insight, Lawbringer, Obedience and Voice of Reason. There are also two good crafted weapons - Hit Power and Blood. You can also use Charsi’s quest to make a weapon, how good it is is random. There is also gambling for rares that can be upped in the cube for good damage if it has beneficial affixes.
First use an act 2 offensive merc (Blessed Aim), then switch to a Nightmare offensive merc (Might). If playing ww get your merc an Insight asap. Damage isn’t important on barb mercs, their auras are all that matters. The absolute best auras are a might merc using an Infinity. Second best are either Pride or Reapers.
The safest way to kill council before you’re geared well is slow but very effective. Use taunt to draw out one at a time counsel minions past the ponds to the middle of the screen where the steps are to the alter. Get the Super Uniques to chase you back to the steps. Be careful when your character is amped! Don’t that a hit from exploding bodies upon their death - Cold and Fire enchanted while amped.
The fastest way to kill all the counsel with a barbarian is using WW, Might/Infinity merc and amp them using GoP charges on switch. With a good weapon/s they’ll all drop like a group of flies from a blast of Raid.
Singer is the cheapest build.