Once you learn the fortress (it took me many dozens of deaths) it's really easy. My best advice is to learn how to time the swinging axes and never fight on the catwalks. There is absolutely no reason to. Every fight that it appears you might have to do on them, can simply be strafed around and run past. I can make it all the way to the bonfire only fighting 1, maybe 2 snake guys directly, depending on how lucky I get of them running into traps on their own. Once you learn where the traps are, they're more useful to you than harmful. A fog ring or invisibility spell can help a bit, as well, but the enemies will still hear you and take blind-ish shots if you don't have hush/the silent walking ring.
I actually had someone summon me at the top of the fortress the other day, I expected to help them with the golem, but instead just ran around with them fighting invaders(mostly blue). Got a ton of souls for it before he stupidly fell off a ledge and died.
Fun times.
@facekillz Im not as experienced as some people here, as a matter of fact im still doing my first playtrough but i really dont recomend getting the drake sword, or get it and dont use it, i mean we are playing this for the challenge and that sword is basically OP for half the game.
The way you play is entirely up to you, but this is one of those games where you don't lightly turn down any opportunity improvement you can find. I have gotten to the point where I try non-standard and specifically crippled builds just for fun, but I rarely get them past the second bell just because it is that hard. Even with the drake sword, the game still doesn't let up and even fully improved, which is tough to do with the upgrade material being dragon scales, the drake sword still isn't that great. It's a very good early game weapon that can be cheesed off the drake pretty easily, but it doesn't make enemies hit any less hard. Even so, it's not all that different from a +5 raw longsword, which can be created right at the beginning of the sewer area as long as you have time to grind enemies for the titanite. And while it may not seem like all that much at the beginning, unless you're going for a large weapon wielding character, those levels in strength needed for the drake sword could be well used elsewhere. Once you're up into the hundreds, with each level taking well over 100k souls, you'll wish you'd rethought your early game a bit.
It all depends on your playstyle, and there are as more playstyles in this game than most people will ever have a chance to try.