Do you have any recommendations for spells? I have a few things that need protecting from this guy.... hahaha.
It's hard to say, I prefer to be very specific.
I have also started on a glass of wine, so go easy on me here
If I had a nosy landlord, I would go for a style of protection that is more ignore/invisibility than "back off". Your landlord sounds a little jumpy so any protection that is aggressive could make him feel uncomfortable and that could rustle up more trouble.
I would use imagery like Cover, Disguise, Ignore, and Boring, as opposed to imagery like Secret, Hidden, Off Limits, or Back Off.
I'd combine magic with a lot of mundane covering up. Like there are cute methods for creating your own book covers out of wrapping paper that you could use to cover all of your 'inappropriate' stuff. Personally the covers on most modern magic/pagan books make my eyes roll out of my heads so I like this solution. You can modify some props like candleholders with decorations that are charmed to say "I'm a hipster candle holder from Pinterest, nothing to see here!" as opposed to, "hey, this chick has way too many candles, isn't that odd." (Personally, I think that 'Pinterest culture' is an amazing excuse to start collecting tons of unusual trinkets and redecorating). Items that really can't be disguised, like pagan symbols or tarot cards, can all be kept in a box that is enchanted to discourage people from opening it (also, hardware stores sell locks that can save on a boatload of magic). If some of the containers really fancy, I might go with a "this is too delicate to touch" vibe. You could knit/weave/crochet/sew a tie to wrap around closet or cabinet doorhandles so people don't want to touch it or open it. For this, I like a "opening that door is too much trouble for me" vibe.
The way I would approach it is to recover/reupholster everything so there are no titles like WAY OF THE WITCH accidentally sticking out of my bookshelf, then find a real organized home for everything (I might go as far as to magically "stick" the items to their home if I was always losing them). For items that I had out and on hand regularly such as a journal or tarot decks, or things that can't be kept in cabinets, I would further enchant the container or it's home to look very common and normal, and to make people think, "eh, whatever, that's not interesting to me at all." If I was feeling sneaky I would run counter intel by making some items extremely interesting so that a person is likely to focus on that to the exclusion of everything else.
I'd also have a long talk with my things and my room and explain to them exactly who and who not is welcome. I would talk to containers or closets and tell them who is not welcome to look inside. I would tell magical items who they need to hide from.
I think part of the reason I have started cleaning so much since I started the path is that a messy room makes me paranoid something 'witchy' is out when people visit. So a good clean-up combined with instructing the room works really well for me
I'm not sure what you are looking for but I hope this helps!