Relax! Your cat will reflect your emotions. If you are anxious, your cat will likewise react. Relax and be calm. At lease initially, it might be helpful to have another person available in case you need assistance. 

Prepare all of the medications that you are about to give, before you fetch your cat. Tablets and capsules should be individually set out and liquids drawn up into an oral syringe. It might be helpful to coat tablets with butter or some other savory substance such as tuna or anchovy paste. This not only makes the medication tasty, but also lubricates it, which might make it easier to medicate a reluctant cat. 

Placing your cat on a slick or slippery surface, such as a smooth counter or tabletop will help to keep your cat from getting a grip with its claws and running away. Alternatively, it might be helpful to wrap your cat in a towel or blanket to restrain its legs.

Approaching with your hand from the back, or top, of your cat's head, gently and calmly grasp the top of your cat's head, positioning the tips of your index finger at opposite corners of the mouth on your cat's upper lip.

Gently tilt your cat's head back, so that its chin is facing upward.

With your other hand, hold the pill between your thumb and index finger, and place downward pressure with your middle finger on the front of your cat's lower jaw. Combined with the upwards head tilt, this will cause your cat to open its mouth.

Quickly place or slide the pill as far back in the mouth or down the throat as possible. If positioned far back in the mouth, it is unlikely that you cat with spit it out.

If giving a liquid, do not tilt your cat's head upward. Place the liquid filled syringe just past the lower teeth. Slowly squirt small amounts into the mouth, pausing between squirts to allow your cat to swallow.

To help prevent tablets or capsules from becoming lodged in the esophagus, immediately follow the medication with about a teaspoonful (5-6ml) of water which can be administered with a medicine dropper or oral syringe. Alternatively, if you cat is calm and willing, offer a small amount of milk or other tasty liquid to ensure that the medication is washed down into the stomach. Check with your pharmacist to be certain that the liquid is compatible with the medication that you are giving. 

If you are uncertain if your cat has swallowed the medication, gently blowing in its face or gently rubbing its throat will help to stimulate swallowing. 

After receiving medications, some cats may salivate excessively, this is normal and not harmful.