The best house rules for a holiday cottage are those that endeavour to ensure that guests can relax and enjoy their holiday while knowing being confined by draconian terms or doing something unwittingly naughty. Having a clear set of do's, don'ts and responsibilities also makes it much easier to deal with problems that may arise. Use this template of 'acceptable' rules from Lodgify to identify those that you feel will be relevant to your own holiday cottage.
A good policy to adopt is working to create a set of house rules that, in the event of anything going wrong don't leave a good relationship between an owner and their guest still intact (and likely to return) without either party feeling hard done by. Not easy - but this list may help! Above all it they not only apply to an owner's expectation of guest behaviour, they also set out what the guest can rightfully expect from a property's owner.