-make the transition between ceilings and walls as less drastic as possible. similar colors(whether lighter or darker) on both ceilings and walls. You don't have this very clear border-you experience less of that "white lid" effect. If you'd rather have contrast-install moldings..paint them ceiling color..visually, you'll experience it half a foot higher. Tricks the eye like there's no tomorrow.

-Use lights on all levels-table lights, sconces, wall chandeliers, floor lamps..against conventional wisdom-ceiling lights might work especially if rooms are too long and expanse of ceiling is relatively too big..there are some pretty flushmounts and semi flash mounts (I usually go for vintage but they started making more new ones nowadays)..or you can put a pendant in a sitting area-somewhere where no one will hit his head..in short, create levels of lighting, and work with a specific room-maybe room X will benefit from having a ceiling light? don't go by general rules always-look at the room in question. Ceiling fans are the hardest to get right with low ceilings-they're big and can feel oppressive

-any possibility of creating skylights? again, besides being sourse of light-makes ceilings feel higher. Immediately. It's like a visual jump.

-make rooms interesting(maybe they already are). have art, plants, bring lots of soft textures, personal details. low ceilings want to be cozy? okay..give them that. make your rooms crazy livable, cozy, and interesting-the eye will travel with pleasure and won't concentrate on how exactly the ceilinng is low. It'll have other things to explore. You'll tend to forget about the ceiling's height-you'll see a room that begs you to stay, regardless. Curtains-take them to the top..art-don't be afraid of big pieces/gallery walls that climb up..have less furniture pieces but bigger ones..embrace what you've got.

And have fun!

(we have 8'' ceiling in our new place-and I'm very not used to that, I grew up differently and all

but some of the above tips I tried personally-because I perceived new ceilings as very low-and they helped. Obviously 7,5 are harder..but I believe you can get to where you still love your second floor quite a lot. Even though it has lower ceilings)