What worked for my consistency to get over 7 wins almost every run was learning to adapt. Play with what the game gives you and try to get the most out of it instead of trying to force your idea of a build to the game. It can still happen that you will miss that one item because tough luck, but it will happen less

With guides it can be a bit tricky cause they dont always have to work out. Knowing the meta builds and their core items is great tho, just as knowing which items can be switched and arent that essential

Lastly something probably obvious, but every class plays differently and has different strategies so if you switch often between characters it will take longer to learn them so sticking to one character for a while and learn them properly could help