I'm not the most experienced player, but I've beaten the game once, and am about to finish a second play through, so I'll give you some advice.
1. Explore everything. Don't be afraid to look around. You might die a little bit more, but you can find some useful stuff in the process.
2. Use a walkthrough sometimes. Even of you're against this kind of stuff, it made the game a bit more enjoyable for me, and it didn't take away the challenge. Look up good builds, or where certain items are located.
3. Figure out all the mechanics. There is a shit ton of stuff in DS that the game doesn't explain. Go to the Dark Souls wiki and research that stuff. Stuff like pyromancy not scaling with intelligence, Sif not being the fifth boss, and that leaving covenants does no harm got me on my first play through, even with a little bit of research.
4. Don't get too attached to your souls. There will be those times where you die, go to get your souls, and fall off a cliff in the stupidest way possible. That will happen, and it will be extremely frustrating, but you can always get more souls.
5. You will die. A lot. A loooooooooooooooot. Even on subsequent playthroughs you will die. And the best part is, it isn't the game's fault. When I die, I realize I made a stupid move there. There are BS moments, but most of the time it isn't the game's fault
And last, but not least, remember to have fun. This is a game, remember? If you aren't have a good time, just put the game down for a bit. It took me a few months to beat Dark Souls, and there were times when I put the game down for a couple weeks. Don't push yourself with this game. Take your time. Indulge yourself in the world of Lordran, and have a nice stay
Good luck.