First of all, stop wearing ponytails! Having your hair tied back a lot causes it to become more brittle overall, eventually giving you split ends.
Have your hair trimmed regularly, to keep it growing healthy. This tends to be every 6 to 8 weeks or so for most people, less if you have a short style you are trying to maintain.
Moisturize & Strengthen
Keep your hair moisturized and only wash your hair every few days or so. Use a hair-strengthening shampoo (like Infusium 23, Dove shampoos and conditioners for damaged hair, or Pantene), and towel dry gently rather than vigorously rubbing-otherwise you’ll have fly-aways. Apply a hair serum or leave-in conditioner, paying particular attention to the ends of your hair. Let your hair air dry for a while, and use only a comb to detangle.
Blow-Dry With Care
Be careful with that blowdryer! It can make your hair frizz and split, so only dry your hair on the lowest setting, and just use on your hair when it is damp and not sopping wet. Invest in a good styling brush to help manage your hair while drying, and use the brush only on hair that is dry.
Hot Oil Not Necessary
Hot oil treatments aren’t necessarily needed, especially for someone with an oily scalp, but an occasional application of hot oil is fine. Just plan to do it maybe once a month, and before you wash your hair. But make sure to get it all out when washing, or else your hair will get dull and flat! The best way to know that you’ve gotten it all is by when washing your hair, you hear a squeaking sound when tugging your hands through your hair