In Majula, to the right of the sewer where you go to get to Heides tower of flame there is a footpath leading up the hill and around back. At the end of the path is an altar for a covenant called the Covenant of Champions. You can join it from the beginning of the game. Among other things it makes enemy spawning infinite. It does however make the enemies a bit tougher, the upside being that you get more souls for killing them. I went through the game and only farmed each area until the enemies stopped spawning and I ended the game somewhere around 180. At that level I was more than a match for anything the game threw at me (although I'm told the dlcs are harder, I haven't had the pleasure yet). Don't be in too big of a hurry to level up because there are enemies that basically disregard how many stats and toys that you have and will -blam!- you up whether you are level 5 or 500. Learn how to fight well, then all your extra levels will just make sure you can take down your enemies faster.