For the mane, pull a little every time you're out there. Or you can try a thinning comb. Also, I recommend avoiding scissors since you get that "this was obviously cut by scissors" look. Try a razor or if you DO use scissors, flip the mane over on the other side, trim/cut, and then brush back to it's usual side.
You want to pull it after exercising so the pores are nice and open and there isn't any ripping.
Leave in conditioner helps to make it silkier which will help the tail. I use a paddle brush to brush out my horse's mane and tail and forelock. Starting at the ends to get the knots off, then brush as usual.
Don't brush when wet, and make sure to use a detangler.
Hope I helped
"Strength is the ability to use a muscle without tension"