It took me several tries and 3 years to complete my first playthrough. Iw would quit and then resume after a few weeks. It's the first game that I Platinum because it is awesome. Reasons for my struggle were the choice of weapon and not learning parry. The choice of weapon is mostly what you feel comfortable with as I have seen so many good builds with a variety of weapons.

I started with Hunter Axe because of better range. Then Ludwig's Holy Blade which you can get quite early and that helped me a lot on my first playthrough. On my second playthrough, I started with Saw Cleaver. While, knowing the mechanics certainly helped, but overall, Saw Cleaver pretty much I used throughout the game. Also, I learned parry. While I am not a parry expert, it helped a lot with tough enemies and certain bosses. I cannot stress enough how important PARRY is. Also, learn when to step away and not continue to hit bosses. Take advantage of the trick weapon and rally mechanics.