I remember last year returning something to Bass Pro, when I overheard a gentleman telling the employee at Bass Pro that his reel was broken. I looked over and saw a baitcaster sitting on the counter. The reel representative came over...toyed with it a few seconds, and said it was fine. The gentleman tossed a confused look and didn't understand what was wrong. Long story short...he didn't set up the reel correctly. With a little up front work and some practice...this type of situation can be avoided, and there is less chance that you will toss the baitcaster to the side and forget about it.
Every baitcaster on the market today has several characteristics that need to be dialed in before you even make your first cast. The drag, spool tension, and the braking system all need to be set to the lure that you are planning on throwing.
The drag star is located on the handle side, usually has 5 or 6 spokes and clicks when you turn it. It is used to set the drag of the reel by applying more tension to the spool. I usually turn it until it's snug and give it one more 1/8 of a turn. Some people run their drag a little loose, but for most applicatons around here you shouldn't have an issue running the drag tighter.
The spool tension is also found on the handle side and is usually a small cap or knob. This knob puts tension on the spool when the spool is disengaged by the thumb bar. With a lure tied on, and your rod tip about 8 o'clock you should set the spool tension so the lure falls slowly under its own weight. Let the lure fall until it hits the ground...and the spool should stop spinning. If the spool continues to spin, tighten it up a little bit more.
Now comes the most trivial part...the braking system. Your reel comes with one braking system or two braking systems. Magnetic braking systems are on the non handle side, and can be adjusted externally on the reel with a knob. Magnetic brakes can be found in most Daiwa and Lews reels. Centrifugal brakes are also on the non handle side of the reel and can be adjusted by taking off the non handle side plate of the reel. Once the side plate is of there is usually a set of counter weights. When the counter weights are pushed out...more braking. When the counter weights are pushed in...less braking. Centrifugal brakes are usually found on Shimano and Quantum reels....with Quantum reels being the oddball because their centrifugal brake can be adjusted with a knob on the outside. Some reels have both magnetic and centrifugal brakes...such as the Bass Pro Pro Qualifier, Lews Tournament Pro, Revo STX, and Pflueger Patriarch.
When you set up a brake system you always want to start with the braking system fully engaged. So for magnetic brakes...that dial should be turned on as high as it can go. With centrifugal brakes, the pins should all be pulled outward.
Last thing you need to do is get your thumb ready to go....your thumb is the one thing that will eventually allow you to become great at using a baitcaster. Train your thumb, and you will be less likely to rely on the braking system that the reel provides you.
Before you even go to cast for the first time you need to forget everything you have ever done with a spinning reel if that was your strength originally. Baitcasting and spinning setups are two different animals and DO NOT cast the same. Press the thumb bar and hold the spool with the thumb of your casting hand. Let your thumb "feather" the line as the lure drops down to the ground. Just as the lure is about to hit the ground, stop the spool with your thumb. Repeat this several times until you get a feel for your thumb starting and stopping the lure.
Next you want to make a roll cast...or side arm cast. Use your thumb to release and stop the spool as you already did above. It is important to not let the rod tip "follow" your lure on the cast...try to keep the rod to the side of you during the cast....this will allow the bait to head straighter to your target. Once you get a feel for this...you can start to dial back your brake system. Turn the dial a few ticks back on the magnetic brake, or push two "opposite pins" inward to disengage them. Centrifugal brakes you always want to disengage in pairs. If you have a dual brake system....always start with the magnetic brake and work your way into the centrifugal brake.
Now comes the hardest part to learn...the overhand cast. The mystery behind this cast is all in your release point and the follow through after. When you release the bait your thumb should be coming off of the spool around the 11-12 o'clock position....and on the follow through your rod should hover around the 10 o'clock position. You never want to follow the lure down in the follow through...or your lure will dive bomb right into the water....same will happen if you release late.
If you are just starting out I would recommend practicing with a cheap monofilament. I know the temptation is there to jump into braided line because you heard it is easy to learn on....but I gaurantee you will not want to swallow a birds nest of 30 dollar braid. Braid can be a bear to pick out on a bad birdsnest.
Take your time, and be patient! It took me 2 years to get pretty good with it, and I still get bad birdsnests every once in awhile. But the reward in accuracy and casting distance will be worth it! Had trouble in the past throwing heavy lures on spinning gear? Won't be an issue anymore!
Good luck and tight lines!