One is letting go too late the other is too early . Pick a spot in the sky about 45 degrees up and aim at that as that gives you a decent amount of height and distance.
The basics are have a reasonable amount of drop from the tip to the lead 4/5 ft and try to have it roughly the same each time as the drop effects the timing .
Get your leading hand (left hand for right handers )up nice and high with the right hand down as low as the drop will allow lean back and swing the lead out behind you a bit .
Once the lead hits the top of the swing out start moving forward so your body weight is loading the rod as well .
As you move the left hand should be pulling down hard as the right hand is punching up . Getting the timing right is the big thing here as its all happening quite fast.
Once the lead is away follow the line with the rod . I see people but the big effort in on a cast the immediately point the rod at the horizon...the line is rubbing like hell on the rod tip rather then just flowing out in a nice line when you drop the tip down = lost meters in excess friction .
1