I think the most important thing you can do is learn about common structural hazards and keep an eye out for them. Rot, termites, rising dampness, and various other common structural hazards are easy to contain when they’re caught early. You can put an end to wet rot, mold growth, and rising damp with the help of a damp proofing Kent company like this one, for example.
However, if these issues go ignored, the structural damage that occurs will usually be irreversible. And depending on how deep the damage goes, replacing the affected parts may be prohibitively costly or even impossible.
It is also a good idea to keep an eye out for cheap improvements that can make the house easier to live in. There are plenty of DIY insulation solutions that can make old homes much more comfortable and energy-efficient, for example. And the easier it is to live in a house, the less of an incentive you’ll have to sell it or move out.