Adopt a slow,calculating approach. Rushing in will get you killed. Know what your buttons do. Take the time to swing your weapon at the air in Majula to learn the moveset. Learn about equipment scaling,and take the time to read the help tooltips (press "Select" by default on a 360 controller) to understand what does what.
Understand that different builds will perform differently in different scenarios. Some enemies are so resistant to magic they might as well be immune,while some enemies are the same to physical damage. Sometimes,a shield will be your best friend. Other times,it'll be your undoing. Don't be afraid to do a suicide run,just so you can learn what's what. Now,some tips from a veteran who ISN'T a god at the game.
-Infusion is powerful. It modifies a weapon or shield to have new stats. Some attributes (often physical) are reduced,while other attributes are raised,or even newly given. However...
-Infusion is a tactical choice. No every weapon is a good infusion candidate. Some weapons will laugh at their infused counterparts,because their unmodified stats and scaling are just that good. The Sun Sword,and the Fume Ultra Greatsword spring to mind. However,on the flipside,some weapons are purpose-built for infusion,like the Butcher's Knife. Or Handmaiden's Ladle...
-Dodge speed isn't as critical as people make it out to be. While it certainly helps to have a faster roll,it isn't back-breaking on it's own. With proper use of spacing and blocking,your time spent rolling is easily minimized.
-Scaling. Most pieces of equipment improve in effectiveness relative to your stats. You can see their scaling values on the equip screen,with letters underneath certain symbols. From worst to best,the grades are E,D,C,B,A,S. As a note: Weapons with great scaling often have mediocre base damage to compensate.
-Weapons can be...Fragile. Repair powder is extremely rare for the first half of the game. You'll be relying on Lenigrast,bonfires,and replacement weapons until then. ALWAYS pack a backup.
-Keep ranged weapons handy. They can deal a crazy amount of damage,but,more importantly,they allow you to pull,weaken,or even kill select enemies from the safety of range.
-Help Sunbros. If you see a brilliant golden summon sign,use it. They are members of the Heirs of the Sun covenant,and their standing in the covenant is directly tied to how often they're summoned,and succeed in assisting the host. To snub a Sunbro is to deny them their rewards.
-Invaded? Unleash the beast. They didn't ask. You had no say in the matter. Invaders abandoned all pretense of honour and fairness when they forced their way into your world. As such,do everything you can to stack the fight in your favour,without outright cheating. Summon phantoms. Chug Estus like it's Sunny D. And if they whine? Their own damn fault for using such an uncontrolled means of PvP. Tell 'em to use a Red Sign next time.
-If at first you don't succeed,try,try again. Dark Souls is about perseverance. You will likely hit a brick wall. Remember that it's a wall. Walls can be torn down. Either keep at it,or find a different way. Learn from your mistakes. The game very rarely cheats. Oh,and if you find the boss fight for the Ancient Soldier Varg,Old Explorer Ceraph,and Afflicted Graverobber? They cheat.
-Death or glory. If an opportunity presents itself,seize it.
-It won't get easier. The game doesn't compromise. You need to step up if you want to conquer it. It'll make you earn it. But,when you do? You'll feel GOOD.