Fair casts are made with decent fly rods. Good casts happen with good fly lines.
Great casts come from both… and practice.
A good, slick, straight fly line will do more for a mediocre fly rod than a fancy, expensive fly rod will ever do for a tattered, mediocre fly line.
Clean the line with a soft cloth and warm water. Straighten the line by stretching it out. If you don’t fix the coils as they come off the reel, casting is like trying to push a corkscrew through a drinking straw.
And replace the line if you cannot reasonably accomplish either cleaning or straightening it. You don’t need a super-expensive line, but even the pricey ones cost less than a new rod.
And once your line is right, practice. Most people wouldn’t head to the golf course without hitting the range first. Why would you make your first cast a “fishing” cast? You are the real difference maker and you can do great things with a little practice!