Tyre pressure, tread and engine oil levels should be checked regularly. With your tyres, it's important to remember to check the spare, and know that you should only ever check the tyre pressure when they're cold, or else you could get a false reading.
Engine oil consumption will vary depending on your car, but you should always keep the levels topped up. Bear in mind that an excessive amount of oil being used could be an indicator of a bigger engine problem - if you're in any doubt, make sure you take the car to your trusted garage.
By frequent checks, we mean every one to two weeks - but the need to check your motor for these things may differ depending on the age and the condition of your car, as well as the type of driving the vehicle is mostly used for.
However, you should always be on the lookout for windscreen cracks and stone damage. Even a small chip can turn into a much larger problem in certain conditions, so be sure to get any damages repaired promptly.