Our house was built in 1905, is about 2100 sq ft and there are 3 of us + black lab here fulltime and stepdaughter on weekends.
My number one tip: get rid of stuff!!!!!
I worried about storage when we first moved in and bought two extra wardrobes that used to be crammed, but now after getting rig of a ton, we could probably get rid of at least one, as well as other now-empty storage units. We already have gotten rid of several previously full storage units including a desk and dresser after decluttering.
My next big tip: built-ins! We have a large built in cabinet in the playroom, a built in bookshelf in the living room and nice to-the-ceiling cabinets in the kitchen. As I've been decluttering I've been getting rid of smaller pieces of furniture b/c these built-ins are far more attractive and efficient.
This is our current storage sitch:
kitchen: 1.5 walls of floor to ceiling cabinets hold all of our kitchen stuff. We also have a butler's pantry with cabinets and a counter that we use for small appliances (nuwave oven, crockpot, etc). There is a small built-in desk area where I keep bills, mail, a file cabinet and safe underneath. We have a small to medium amount of counter space, so we keep counters clear.
dining room: one small cabinet holds serving dishes and bowls, exra cloth napkins, etc. We have a side table where we have a few more bowls and keep mounds of fresh produce ontop for storage/decoration. That's it for dining room things.
living room: we have a built-in bookshelf for books, decorative items, DH's records and player, and a small stereo, and one wardrobe that we use to store all office stuff (stores laptops, paper, printer, office supplies, all chargers, craft stuff, etc). We have an ottoman with storage inside and DD's toys inside, although I could move them to the playroom and have that for other storage if needed-but nothing else to put in it now.
playroom: large built-in cabinet holds: all board games and puzzles, books, fish tank and supplies, all wrapping paper and boxes, few DVDs and CDs we own, and an old stereo that we need to get rid of as soon as DH can bear to. Two short bookcases with books and bins for toys for DD.
master bedroom: small closet holds DH's clothes and my off-season clothes. I have a wardrobe in there that I bought before thinking I'd absolutely need it, but since doing project 333 I keep only one season of clothes in it, so it's very empty and could probably get rid of if I wanted to. DH and I each also have one dresser with our work-out clothes, pjs, socks, etc.
DD's room: one dresser with her current season's clothes in it and her books on-top, a second dresser with off-season clothing. Her small closet has a few hanging clothes, some toys that I have stashed away, a shelf with her extra bedding, and two completely empty drawer storage things that I should get rid of.
DSD's room/guest room: A large dresser with vanity, half holds DD's clothing and half has some of DH's workout supplies and video games. A small closet holds our extra blankets, beach towels, extra off-season coats, etc.
Mudroom/laundry: above the washer/dryer: one shelf with baskets and bins with: laundry supplies, all cleaning supplies, random household things like lightbulbs, rags, and our iron. We have hooks for coats and bags and above it one shelf with a basket for each of us to hold our scarves, gloves, and small outdoor items. We have a shoe thing, and in the corner or hanging have our mop, brooms, and vacuum.
Downstairs bath: one vanity with extra toilet paper, hand towels and dog shampoo.
upstairs bath: nice sized closet with baskets with all meds, extra sheets for master bedroom, extra towels, first aid things, bath toys, q-tips, etc.
We have an old barn and unfinished basement for yard, garden, and car items, but I try to go through those areas once a year or so to keep them under control.