worst hair ever...help!

What are you using to hold the ponytail at its base?  Terrycloth or cotton elastics, or scrunchies, are best.  Rubber bands are the worst.  Most everything else is somewhere between...

Be careful when gathering the hair for the ponytail to smooth it together well in your hands, before putting on the hair tie.  It can also help to comb or brush the hair in the direction you'll want it to go into the ponytail.  In other words, hold your head up and comb it back (not down), in advance of gathering the ponytail in your hands.

Try slight variations in the location of the base of the ponytail, to avoid putting all the stress on the same spot.

Braiding your hair occasionally will allow you to avoid using a ponytail holder altogether, on those days.

Another option better than bands of any kind is hair sticks!

For it to look good down, I can't recommend what to do to it yourself. It may be worth it to go the salon for a good wash, condition, and blowdry. Tell the stylist that you want to wear it down, and they may have to flat iron it down or something. That may get the "bump" out of it.