Greets!
I havn't played demon's souls and will most likely not, since I am currently an exclusively pc gamer. I've found Dark Souls to reward patience and what I would consider to be safe play.
When going into a new area, I would wiki the area to see if there are any specific points to remember or monsters to look out for, then I just keep an eye open. The specific wiki I use is the Wikidot wiki, I dont bother with the area maps themselves. This means I only know what enemies or specific things to look out for are, not where exactly where they are located.
I then enter the new area in a hollowed state and proceed with as little loose souls and humanity as possible, as well as be as cautious as possible against enemies I havn't fought before. Once i get the hang of the area, I'll then start to do things in a faster and riskier way. Only exceptions are bosses themselves, I wiki up on their attack moves then engage them with as much reckless skill I can muster, until I get a hang of their patterns, weaknesses and exploits.
For example, first time I took on ceaseless discharge, I found that I could get him stuck into the same attack over and over when I stood near the body with the clothing that he triggers on. Due to the predictable patterns of attack, I just kept on hitting him when he threw his arms at me. Never even got hit once.
Similarly, I'll only ever try to pull at most small groups of enemies I can flatten all at once with one swing of a zweihander. Otherwise, most enemies in the game are predictable and respond poorly to someone who is patient. The only enemy I've had trouble with thus far as been the awesomely epic fight I had against the griffon thing that protects the sancturary for the DLC.
While it did only take me three tries, the fight with this griffon took me upwards of two hours due to its unpredictable attack patterns and crazy reflexes. The only real reason I got him in the end is that I figured out how to stun him with a zweihander, although it was damn risky for me to do. It paid off however and I felt better for it.