This is very scary for new people on bait casters, but I've learned from forums and videos to actually keep your spool tension so loose that it's right at the point of the spool sliding (you'll feel it loose and moving) back on forth.
Keep your brakes where you're comfortable, half or even higher.
Just make sure you have your thumb ready.
*** Don't throw the bait too hard, especially light baits. --> A gentle toss with loose spool tension and good brakes can send even light baits a long way. But throw too hard and it's backlash city. And at the end of a long day fishing with hundreds of casts, you'll also be less worn out from throwing as hard as you can to overcome the tight spool tension and high brakes.
Also, as others said, make sure your line is spooled on tight.