Rule of thumb is to save ~1-2% of the purchase price each year for necessary maintenance and repairs.  Roofs need replacing every so often.  Decks need refinishing and repainting.  Windows need repainting, resealing, or replacement.  Things break.  And so on.

Learn to do basic maintenance.  Don't stress about not having every tool: just buy them when you need them so you don't end up with a bunch of crap you never use.  Exception: basics like a socket set, screwdriver set, hammer, drill, etc.

That said, the problem with houses is that one can spend infinity dollars on them.  There's always something more you can do, something nicer you can buy.  So you have to ask yourself: What matters most?  What do I use multiple times every day? 

Some ideas that work for me:

It's worth having nice new toilet seats: they cost maybe $10-$20.  I replace these even in rentals because they're so cheap.

It's worth having a nice bar-style kitchen sink with the elevated sprayer.  You don't need the $500 German ones, but the $80 ones off Ebay break in a couple years.  They're not hard to replace yourself.

It's worth having a dishwasher that actually gets your dishes clean.  You don't need the $1500 German ones, but you should probably get a Consumer Reports online subscription so you can know what the best appliance values are.

It's worth having a nice mattress.  You sleep on it every night.  Sleep is important.

Get a nice showerhead that sprays the way you like.  Showers are therapeutic as well as functional.

Make it yours by painting the interior whatever goddamn colors you want.  Have fun!  You'll have to repaint anyway if you want to sell it.  Note that rooms which get direct sunlight often work best in cooler colors, and rooms which don't often work best in warmer colors.  Painting is not rocket science: cover the floor with old sheets, mask the windows and the trim with masking tape, get a roller and an edger, and go to work.

Buy furniture used off Craigslist.  The depreciation is about 90% on all furniture.  I got a really nice sofa and ottoman for $100 that was clean, just a few years old, and probably cost someone at least $1200.

A decent 40" LCD TV should cost you well under $500: 50" and up is where they start getting spendy.  Newer TVs will all hook up to your computer, so it's just like having a huge monitor.

"If it's important, do it every day.  If it's not important, don't do it at all."

Ironically, the key, for me, is to not sink so much money and time into my domicile that I'm tempted to stay in a terrible work or other living situation just because I've spent so much on it.  Investing only what I can walk away from gives me the freedom to enjoy it on its own terms — not "I feel guilty about eating out because we spent so much money on the new kitchen" or "I can't go on vacation because we spent so much on furniture".  At that point you've sucked all the joy out of ownership, because your possessions are an obligation, not a pleasure.

Would it be wonderful to live in one of the six-bedroom mansions on the water?  Sure…but then I'd have to have been working hard enough for decades to make the millions of dollars required, I'd have to be the sort of person who preferred that to skiing and riding and doing nutrition research and writing The Gnoll Credo, and I wouldn't have done any of those things, and gnolls.org wouldn't exist.  I'd be just another rich guy in the Bay Area rat race with a huge house he only uses one or two weeks a year.

It seems counterintuitive, that spending less and having less allows you to enjoy more — but I find it to be true.

JS