Not sure if you liked two handing in DS2, but it's very specific in DS3, where you have to get a "weapon" that is really two weapons, in order to properly two hand. But since you're a knight I doubt you're all that interested. I won't spoil it, but if you talk to the turtle hermit guy, and take him up on his offer, you'll find out what the difference is between being hollowed and being unkindled/enkindled is for this game

But yeah, I like the idea that you're character is one of thousands who linked the flame previously, and one of thousands who was re-awoken because you succeeded once, and they need you again, because the heroes are being stupid. Once you get most of the way through the game, there's a really good Game Theory video about who your character is actually supposed to be, and I kinda like their theory. But it won't make sense until you encounter a lot of things in the main game, so I'd only watch that once all the main heroes are defeated

You probably already know to save boss souls, you'll get a thing for that later. You probably already learned you can manage different types of flasks, and as a melee character you may not even need the blue flasks, so you can max out on yellow flasks. Though I hate that they share a pool. It kind of gimps mage classes. Much prefer the old way where spells take stamina, and have charges. So it's not a drain on estus

And I doubt you'll have too much trouble with going solo. The only bosses I ever needed a friend with were halfway through the game, and the one has like 3 NPC summons right outside his door. So that's no problem offline. Aldrich may be a problem, though. I can give you more specific advice when you get to him. I don't think there's any NPC summons, and last time I tried, there was nobody available to help. So PS+ would probably be useless there. I've always had to solo him except for my first run through of the game. And he's quite the anti-thesis to a lot of character builds. So it can get tricky until you get used to his BS