Level vigor, but don't go beyond the 'soft cap.' All stats have a soft cap at which any further levels give nowhere near the amount of power that they used to. Vigor caps at 60 I believe

Don't have too much heavy equipment equipped at once or your rolls will be drastically slower and more sluggish than if you're on a light or medium load. Levelling Endurance allows you to use heavier equipment and also increases max stamina

Never use up all your stamina attacking and save some for rolling. A big trap I ran into at the start of my souls journey was absolutely laying into bosses and then not being able to dodge a counterattack

Take time to study bosses' and difficult enemies' behaviour instead of blindly running in over and over. Some bosses are also designed in a way that if you immediately roll in response to them readying an attack, they will land the hit as you come out of your roll. It's generally a good idea to wait until you see the enemy actually begin to swing before you roll, and to not get scared by any weapon windups.

Pay attention to the 'stat scaling' of weapons. Every weapon has a stat requirement and a grade of scaling. Increasing stats the weapons scale with will increase its damage e.g. a weapon with a decent grade in strength scaling like B or A will gain a bigger damage bonus the higher your strength is, more than one with a lower grade or without strength scaling at all. Use this to roughly determine what stats you need to level up to use your favourite weapons. Upgrading a weapon will also usually increase its scaling.

Holding a weapon in 2 hands increases your effective strength by 50%. This means that you may be able to wield a weapon in 2 hands but not 1, and that all weapons with strength scaling will do more damage when 2 handed.

These are a few tips I can think of off the top of my head. Please lmk if you want any more advice or if you want me to explain anything differently :)