While some attributes are better than others, any civ is as capable of success as any other. You can warmonger effectively if your civ is commercial and expansionist, and be a beacon of knowledge with a militaristic civ. Theres really no best civ.
For a new player, you'll want to look for civs that are Industrious or Religous, as they are widely considered the best attributes. Next is scientific, expansionist, and then commercial. On paper commercial would look pretty handy, but its effect on corruption is so miniscule its really not worth it. Wheres militaristic? Somewhere between scientific and expansionist, it comes down to player preference.
If you're having trouble staying current technologically, its worth mentioning that you have to trade/buy technology with the AI nations early and often. If you try to research everything yourself, you'll fall very far behind.
For some basics on early warmongering see this thread