I really liked this character because of the cool armor, move-set with the weapons as well as the badass label of being a mercenary! This is the most I've ever been invested in a Dark Souls game and I'm almost at level 100. Some early advice for newbies that just want to get better at the game in broad strokes:
1. Level up as often as possible, not only in health but in endurance ( I prefer like a 3-5 level difference between the two)
2. Stick with one weapon and collect as much titanite as possible. Try to also look for the raw gem as this will help a lot in the early game.
3. I used the sellsword twinblades and used the raw gem on it. After a couple bosses, I actually switched to the sharp gem on it as it's a better long-term investment since it scales up with Dex.
4.The most controversial: use your boss souls to level up. I know the weapons are really cool but unless you see yourself using it for a while just use the souls for more important things like leveling up.
5.. Look for estus shards!