The old cliches are generally right. For example, you can change everything apart from the location and fundamental structure (and maybe even the latter). Buy the worst house on the best street, not the best house on the worst street and so on.
Apart from that, it's largely a matter of taste.
My rules:
1. Don't overextend yourself. Don't get bigger than you need, because you'll just be paying to heat it and furnish it for no reason as well as committing yourself to more debt. Don't think about how much you /could/ afford, think about the least you need to spend to get want you /really/ want (rather than the nice-to-haves). That way you can enjoy some spare cash each month and also have a chance of paying it off before you get too old. If and when you have spare money, pay off your mortgage as fast as possible. And invest anything after that in something /other/ than the place you live. If you really must be maximised in property investment, do it via a second property or property fund, not your own home.
2. Tracker mortgages are better value than fixed mortgages. Fixed rates are essentially insurance against rate rises and, like all insurance, there is a premium to be paid. If you followed rule 1, you should be in a position to absorb a few points of rate rise should the unexpected happen (expected is no more than a 1.5% rise over the next 5 years) -- in the long run, this will prove cheaper than the few years of protection the fixed rate gives you. Tracker mortgages also allow you to pay off as much as you like each year too -- again, remember rule 1.
3. The climate is changing. Don't buy anything near rivers or the ocean. Or a cliff. And while I'm on the subject, avoid anything with known problems, like subsidence. This is an absolute rule, do not break it at any cost for any reason.
4. Property is easy to buy and tough to sell. So if anything smells wrong, don't buy it. Sitting on a property for 18 months whilst nobody puts in so much as an offer is as depressing as hell. If you can see an issue, so will others. Do your legwork -- if people have made unauthorised changes, if there is an unlicensed septic tank, if there is problems with parking, these things will all cause you headaches.
5. Know what you absolutely definitely want and don't compromise on it, regardless of how good the estate agent is at selling the alternative. If you must have a garage (not me!) then don't get something without a garage. If you must have south facing, get south facing, if it needs to be a period property then don't buy something from the 1950s.
And MOST IMPORTANT of all:
6. The only rooms you really care about are the kitchen, the lounge and your bedroom. This is where you will spend all your time. You need space to cook in and eat (the latter may be via a dining room but a kitchen is generally preferable), you need space for you and friends or family to sit and you need room for your clothes and bed. Everything else is going to be used intermittently at best. I've had conservatories, basement conversions, loft conversions, you name it. They all were little more than store rooms in reality. DO NOT under ANY CIRCUMSTANCES compromise on the three key rooms because you get a basement and a conservatory. This is a one-way ticket to malcontent.
Hope that helps! In 18 years, I've bought four houses and three flats, and I've failed to buy a whole bunch more. This is what I have learned from that experience.
