My wife and I currently reside in the suburbs of north San Antonio, though our hearts are most definitely out in the middle of nowhere (somewhere :) ). After eight years living here, we put our home up for sale last week with the plan of moving to some land far away from the city (but still close enough to visit frequently), where we can see every single star in the night sky and not have to ever hear the sound of a car driving down the road.
Now, just because we weren't living on the homestead we hope to have one day, don't think for a minute that we didn't homestead anyway! Let me give you a brief tour of some of the things we've done and are doing.
For the first five years, we kept three to five hens in our backyard. 
(against Homeowners Associate rules, of course! That's just how we roll ;) )
Since water is such a precious resource, especially here, I re-routed our AC unit to the overflow on the back porch and harvested the condensation from our A/C unit into a 275 gallon container (took about 6 weeks to fill during the summer) 
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As far as gardening goes, we have been non-stop experimenters. We built a keyhole garden, because we learned that keyhole gardens are really great at water conservation and are well suited for hot areas like ours. 
We built a small hoop greenhouse one year in order to experiment with growing veggies during the south Texas winter. 
When we had the greenhouse up, we also began experimenting with solar power in order to learn all about that and the associated electronics. I have a degree in electronic engineering, so I already had a leg up on it, but without having ever actually DONE it, it was all just theory. We used solar to keep two batteries charged which in turn powered a fan to keep the air moving through the greenhouse during the hotter summer months. Reading about it and doing it are really night and day...I learned a LOT of useful info with that one!
I attempted what is called "air rooting" on a branch of my pear tree that I knew I would be pruning anyway, in order to start a whole new tree:
We also did a LOT of container/bucket gardening, tried straw bale gardening, planted lots of landscape plants that are edible, invested the time and money to learn about real permaculture subjects like burms and swales, and BUILT burms and swales to capture and focus rain water. 
We of course started experimenting with composting...
We planted two baby Concord grape vines and built a walk through arbor for them (which they have taken to quite nicely over the past six years!):
I am a seed FANATIC, and am always planting seeds from wherever I can get them! As a result, we have a pretty good collection right now of baby trees that we plan on nurturing until we can plant them on our own permanent homestead
We have baby apples:
We have grapefruit and oranges:
Texas Persimmon (grown from seeds I harvested from old coon poop! :D ):
A young mulberry tree:
And not pictured are some lemon trees, Sea Buckthorn, JuJube, Pecan, and probably a few more I'm forgetting about. :)
The mother of all suburban experiments was the time I wanted to try aquaponics indoors. I asked my amazing wife for a huge favor: let me hijack our master bathroom garden tub for two months so I could do an experiment. She's so awesome and with only minor hesitation (and a few stipulations), said yes! So I took the cast net and went to a local lake one weekend, bringing home around six wild blue gill. I put them into the tub along with an air stone and a submersible pump, created a grow bed from a six foot length of large PVC pipe, and suspended a grow light above that. 
Bearing honorable mention here are also my several years now of experimenting with homemade wine (which I will always lovingly refer to as "hooch"):
and kombucha:
I know for sure that there are probably fifty OTHER things we've done along these same lines...oh yeah, making colloidal silver and homemade essential oils...I could go on and on! But the point of this post for you is this: let yourself be inspired by others to go out and learn about and try new things, no matter where you live! Acquire those skills, translate that "book learnin'" you're getting from the internet and Youtube and what not into some practical real world experience you can tuck away into your life bag!
You can do permaculture and homesteading no matter WHAT size space you live in...all it takes is creativity, but more so, inspiration. If it wasn't for Youtube and Dtube and Steemit and Facebook and a host of other sites where smart, creative people congregate and share their ideas and stories, I wouldn't have had half the inspiration that I have. I've learned so much by doing what really amounts to "micro experiments" that now when we finally DO move to a larger space (currently have our eye on 32 acres), we will at least have a clue as to what we're doing.
I know that at least some of the things I shared above sparked something in you...piqued your curiosity. Follow that spark! Fan it, get yourself onto a search somewhere and find out what other people are doing! One excellent example to follow is my good friend (and great inspiration) @DaddyKirbs. You should definitely follow him, and see who it is that HE'S following, too. Oh, and follow me as well. :D
Thank you so much for your time, I know you could've spent it doing something else! Your comments and suggestions and ideas are greatly appreciated.
Sincerely,
BiohackerPro (aka, Doug)