There is actually a number things you should pay attention to when looking for a house, not all of these are in regards to the house as well. Here are some general things to watch out for:

1. Check to make sure it hasn't been used as a grow-op / meth lab. Get someone to investigate the home to check for structural issues, and other hidden problems that may otherwise be missed / not mentioned by the home owner or the real-estate agent.
2. Water pressure is a big one, it effects simple things like watering the lawn, washing the car, taking a shower, etc.
3. Inspect the build quality and roof, leaks suck and having to replace the roof is a decent sized investment ranging from 13,000 all the way up to 50,000. Also, note that houses with more complex roof designs have much higher re-roofing costs.
4. Don't get a house with a swimming pool unless you're 100% sure you will take care of it. Remember it's expensive to maintain, and has to be done year round. Many people list swimming pools as an asset when selling a house, but trust me, unless you're a water baby, it's a lot of work and extra cost (heating, chemicals, maintenance, repairs costs)
5. Always check all zoning documentation, if it has a basement be sure to double check if the land is right for it, the last thing you want to be stuck with is a leaky basement with thousands of dollars of repair costs.
6. Never just settle on the asking price, be sure to find an agent that will fight for your price. Agents make money on commission and the work required to earn it. Lazy agents will push you to buy at a higher price because its less work for them and higher commission. The agent on the sellers side does the same thing, they will always attempt to do the minimal work necessary to earn their commission, so don't be a sucker, make them work for their money. If you need to look at 20 houses before you are 100% sure, look at 20 houses, you don't own them anything. Be sure to do your homework on the agent you do choose however, there are some really bad apples out there.

Ok, thats what I could come up with off the top of my head. Hope it helps.

First off, check if you should be buying at all at this point. Obviously it seems like the logical thing, but it can be a millstone around your neck if it's not right for you at the moment. There are numerous sites which will help you weigh it up financially, like this. Think about how long you want to stay in your first place and if you can afford to buy somewhere you're going to want to make a long term home. How long you want to stay can certainly affect how good a deal it is.

If and when you do go for a house, make sure to check a number of things. If you're renting at the moment, think about the things your landlord will take care of - that safety net is no longer there.

Be sure to think about the following:

Electrics: is the wiring okay? Do the switches work, etc.

Roof: is there any discernible damage from the outside?

Damp: check the outside walls for signs of damp. If you can, get access to the attic as well. Look for dark patches and condensation.

Insulation / double glazing: is the house at all energy efficient? Your bills will be higher if you're spewing heat out of the windows. Remember heat travels up, so is there loft insulation?

Space: is there enough of it for future developments? If you're single, what if you get a live-in partner, etc.? You don't want to have to move based on smallish changes of circumstance.

Parking / surroundings: do you like the area? Are there reasonable amenities nearby? Is there somewhere for you to park with little hassle? What about visitors? Is the house on a flood plain etc.? Speak to the neighbours - do they have any gripes?

Internet: are you in a reasonable area for internet? Is there a provider monopoly locally? Can you get fast enough speeds? This one may seem frivilous, but it may be quite annoying in time to come.

I'm sure my list is non-exhaustive, but it should act as a good starting point and help get in the right mindset.

don't take advice from me unless you want to live in the middle of alaska with no (constant) electricity, no plumbing, and a 5 mile long unmaintained driveway!

on the plus side, I don't have to worry about water pressure, wiring problems, swimming pools (I do have two nice ponds though), or zoning. The property actually is zoned, but here are my limitations:

1. under no circumstance can I have a correctional facility or prison on my property.

2. If I want to have a nuclear power plant, I have to pay (I think $500) for a permit. I won't get the permit unless it's stamped by a licensed nuclear engineer though.

The big one my realtor mentioned to us was to have the house radon tested. Apparently we live in a heavy radon area and that's the leading cause of lung cancer in non smokers. Found slightly high levels here so the old owners put in a reduction system as part of the closing. Depending on your area, definitely ask about this.

One thing I would recommend is to set your finances straight. When all the appropriate levels are tended to and you move in, you will want your home to be the center of your finances; so don't purchase anything you can't afford. Also make sure you clean up all other debt: car loans, credit cards, and school loans. You will need to set money aside for necessary equipment and repairs. Also, you might want to throw a bit of cash towards the principal whenever you get a chance; it's amazing how $100 dollars a month will accumulate over the years.

Also when house hunting, never settle for the first place you see.

Good luck and remember to take your time.