Keeping your cat's ears clean is important, and it should be part of your normal grooming routine. Bear in mind that you should only ever clean the parts of the ear that you can see - if you're concerned about an ear infection or any other problems, speak to a vet rather than attempting to remedy the problem yourself.
Start by checking in and around the ear for grass seeds, mites or anything else caught in the hair, then wipe around and inside the ear gently with a warm, damp cloth or flannel, looking out for any signs of infection such as blockages, leaking or excess wax. If you notice your cat losing its balance or shaking its head a lot, there may be an ear problem to address, so make an appointment with your vet.
Cat eyes should be clear and bright, and you should check them occasionally for signs of vision loss or other underlying problems. Face your cat towards a light, such as a bright window, and check in each eye for cloudiness, change in colour or dullness of the white area around the eyeball. Look for any redness or irritation, and wipe away any discharge or tearing around the corners of the eye with a soft cloth or cotton ball. You should also speak to a vet about why this is happening.
With long-haired cats, you should also ensure that there is no hair falling over the face and eyes, as this can be irritating and harmful to your cat's vision if left un-trimmed.