I've played all 5, finished all of them except Demon's Souls (not that it's any harder than the rest, just put it down after a few hours).
Bloodborne is an odd case, on one hand I'd recommend it to newbies as it streamlines the formula greatly (no carry capacity, no class choices, etc.), but on the other hand I find it the most challenging game in the series (it has the only boss in the series I cannot beat, people who've finished the DLC will know the arsehole I'm referring to).
For a newbie, I've got 3 tips:
1) Explore. If a boss or elite enemy is repeatedly curb-stomping you, back up and explore the surrounding area, chances are you'll find items to help you in said fight, or even entire optional levels to go through and get more XP to make yourself stronger.
2) Ignore Bloodtinge and Arcane. It's the same in Souls games, HP, stamina and physical damage should be the only thing a first-timer worries about. Investing precious upgrade points into Bloodtinge or Arcane is taking points away from the vital stats. Arcane is useful, but only if you know the items and weapons that take advantage of it. I've never found a use for Bloodtinge, aside from the two or three weapons that need it.
3) Buy Blood vials. You have a finite number of them, unlike in Souls, so eventually, if a boss is beating down over and over, you will run out (no shame in that, happened to me my first time against the boss at the top of the snowy castle). It doesn't take long before leveling up once costs an obscene number of Echoes, so chances are you'll have some left over. The further you progress through the game, the more they will cost from the shop, so start buying them soon.
Finally, persevere. There will be times where an enemy ambushes you and kills you, where several enemies rush you at once and kill, where you get a boss down to their last pixel of health and they kill you. But just take a step back, ask yourself why you died, and do better next time.
Hope this Souls rambled helped!