A lot of people recommend just playing it any not looking up anything. If you play like that, the game will probably take between 40-80 hours depending on how good you are. Or you can look up stuff like new player youtube videos that show you how to do basic things like dodging, parrying, backstabbing, riposte, etc. If that's all you look up, you'll probably notice a skill increase.
If you really want to make it easier you can look up a guide on the ideal path to go which is what I did. I don't really have time right now to spend 80 hours trying to figure out where to go.
You can go a step further and learn how to beat bosses, where to get overpowered weapons, get optimal weapon paths, etc. This stuff I mostly skipped (I did get the drake sword though).
It's a hard game, any one saying otherwise is just trying to sound badass. Gargoyles took me quite a few tries, and I definitely jumped up and cheered when I beat them.. much like beating Tyson, like you said. It brought me back to the glory days. Coincidentally, there are bosses that some people say take tons of attempts and just assfuck you that I have beaten in one shot (Capra Demon), so everyone will have different difficulties and stuff. Also, as Tuco said, you never really feel comfortable with how you play this game probably until after you beat it once. Even though I one-shot that boss, I'm getting my shit pushed in inside Sen's Fortress - nothing I've learned has really prepared me for it and my skills don't directly correspond to me being any better at the game.
TLDR; bosses are hard, lookup what you want if you just want to beat the game, lookup nothing if you want to spend 80 hours playing.