I wouldn't stick with just tilapia.
There were some (unfounded) rumors that tilapia is worse than hamburgers and bacon, because even though it contains the "good fat" omega 3 fatty acides, but also contains "bad fat" omega 6's. But even though this was not true (tilapia is still better than an equivalent amont of hamburger or bacon), it's still not as heart-healthy as other fish. Someone introducing fish into their diet to improve cardiac health could do much better than tilapia. So experiment with lots of different fish.
I was new to fish a few years ago, and launched into experimentation with all sorts of fish. What I learned in a nutshell:
1. I had always said "I like fish, but not fishy-fish." I learned that good, fresh fish does not smell or taste "fishy" like canned tuna. The one exception is monkfish. Monkfish is yummy, but does smell, even when very fresh, even when you cook it outside, and even in nice restaurants. I gave it about 8-9 tries, and had to give up. Tastes great, great texture, but smelly.
2. I learned that fish is best cooked outdoors. Although the fish I cooked and ate indoors didn't taste fishy or stink, afterward, the house would sometimes stink after cooking it. Microwaving results int he house stinking even longer and stronger. That smell just makes me gag. So I cook all my fish on the grill, all four seasons. All scraps go into the outdoor trash, not the kitchen trash.
3. I learned my cats go crazy when I make fish, and will steal from our plates if we aren't quick.
4. Always, always, always make sure it's cleaned and deboned at the store/market. If they charge extra for this, it's worth it. I hate dealing with pinbones. I tried, and determined that I am inept at removing bones, and I don't care to become an expert.
5. Some inexpensive fish is excellent, but once in a while splurge on an expensive piece--it can be awesome! Chilean sea bass, merlusa, swordfish, some salmon, and some shark can be pricey, but it can be unbelievably delicious! You can also taste the difference between most farmed fish and most wild fish, the wild being better. I had thought this might have been propaganda by gournet-types, but it's really true.
6. At first I wanted it all thoroughly cooked, but gradually, I started eating it rarer and rarer. Sometimes I just sear a good "steak fish" on the outside, and leave it very rare inside. Five years ago, I would have sworn I'd never do this.
7. Invest in a fish basket and a slotted grilling "pan" to use on the grill. this will prevent fish from breaking up and falling through the grill grates. While steak-like fish grill and flip easily without breaking apart (tuna, swordfish, shark) many fish are more delicate and precious pieces fall through the grates. some are too delicate even for the classic fish basket, so the perforated pan works better.
8. Some fish is great wrapped in foil with herbs or a marinade. I also do this right on the grill.
9. When in doubt: chutney. Almost every chutney I've tried tastes great on almost every fish I've tried. I'm no fancy gourmet cook, but a good piece of fish topped with or cooked in chutney tastes like it's from a fine restaurant. Add some long grain rice and you will convince people you're a chef.
10. Taking taste, texture, price and ease of cooking into consideration (in a complicated mathematical algorithm
) my favorite was probably orange roughy.