If you don’t ever plan on moving, or if you simply enjoy the work and the results, the answer to this question might be “there’s no such thing as too much home improvement.” However, most folks won’t live in the same house forever, so there is generally a limit to the amount of improvements that should be made, especially if you intend to sell on your own.
There are some high-return improvements, like kitchen, bathroom, and master suite remodels, that often will bring a higher sale price, but large investments generally don’t pay for themselves. Instead consider small projects that enhance curb appeal, like planting flowers or having your house powerwashed.