First, you should make sure you're getting conditioner that's formulated for your hair. Conditioners for thick or textured hair are going to weigh down fine hair, and conditioner for dry, damaged hair will overwhelm healthy hair.Unless you have a dry scalp (i.e. during certain times of the year), you don't need to work conditioner into your scalp. The natural oils in your hair take care of the first three inches from your scalp, and putting too much conditioner on the scalp will actually can make the hair look greasy and less bouncy.
Don't use too much conditioner on your hair. With more expensive conditioners like bumble and bumble de coco conditioner, you don't need more than a teaspoon of conditioner, especially if you don't have long, thick hair. With your drugstore-variety conditioners you might use a little more, but useing a palmful of conditioner is almost always going to be too much and will make your hair look lank and heavy.
Although most conditioners work best if you leave them in for 3-5 minutes so that they can really repair and moisturize your hair, make sure you wash the conditioner out completely after you let it sit. Rinse your hair with warm water, as hot water can dry out your hair.
Lighter, spray conditioners are a good alternative for people with extremely fine or thin hair. They keep the hair moisturized without over-conditioning, which can happen more easily with lighter hair.
Using a wide-toothed comb while conditioning is another good way to make sure your hair is getting even coverage and isn't getting over-conditioned in some places. Comb the conditioner through your hair completely. This will also get a little conditioner to the roots without over conditioning them.
Conditioner is an important part of a healthy hair-care routine, but it should be done correctly to make sure it keeps your hair looking silky and vibrant rather than overdone.