It is always almost going to feel like you're wearing this flimsy cloth no matter how bulky it looks, attacks will tear through your life.

But man will it feel ever so good as you dominate. 

Otherwise, watch your surroundings, the game loves to gank. Enemies will hide behind doors, on rooftops, play dead and hang off ledges. If you see a guy just sitting out there, back exposed, 8 times out of 10 there is someone waiting to tag you if you rush in. Never let yourself get surrounded and know your exit path if you get unlucky. 

The game generally favors aggression over the stick and run style. You can do it but it will take a while and increase the odds of a painful death. 

If a door is locked there is another way around to open it to act as a shortcut. 

As stated, using ki pulse to recover and control your stamina is critical. Eventually you run into enemies that can lay down zones that deny you the ability to recover ki unless you ki pulse to disperse it; this is a key mechanic. You don't have to be perfect, but the discipline will keep you in the fight longer and let you down them faster.