It sounds good to me, the only thing i'd like to warn you about is that livebearers(i.e platys, mollys, swordtails, guppys etc) produce alot of fry(baby fish) and can do so on a monthly basis, so if you see baby fish in your tank don't be alarmed- your angel fish will most likely eat any fry born though anyways.
When you buy your livebearers avoid getting any females that are heavily pregnant as the move will be twice as stressful for them and they may end up aborting their fry and getting sick or die altogether. The main ways you can tell if a livebearer is pregnant by
a. her gravid patch- this is a dark patch located towards the back of her tummy and is actually the frys eyes you are seeing inside her womb- in mollys though they do not always show a gravid patch and just have a very fat tummy and big chest.
b. Size of stomache, obviously a pregnant livebearer is going to have a pretty hefty stomache and will also somtimes become more unsociable towards other fish and hang around on her own alot.
With male guppys, as beautiful as they are, try to get ones that have the shortest tail as delta tailed males(long tailed guppys), their tails will often rip in a tank that has too strong a current or is too lare for them and they are also very inbred in general.
When buying any fish though, there are certain things to look out for in healthy fish;
Before buying any fish, you should inspect it closely. From an animal's external apperance, you can detect many problems and diseases. Particulary examine the body, gills, fins, eyes and skin.
Body: Any healthy live-bearer's abdomen should look convex, when viewed in a profile. The female usually looks more convex then the male. These fish have a "chubby" look to them. This should also appear in females that have just given birth, even though they may look very slender. All other fish should appear well-fed.
Be careful of fish with protuding scales, and bloated bellies! Most times, if not all times, these fish are incurable.
A large head, that looks disproportionate to it's body, is usually a sign the fish has undergone long hunger periods. This doesn't mean the fish will die, but it shouldn't be used for breeding.
Gills: Healthy fish breathe slowly, although they breathe somewhat faster in a densely populated tank. As the fish breathe, they expose the gill cover. This should appear a pale reddish color, in healthy fish.
Fins: Missing or partially developed fins are ALWAYS a bad signal. Frayed edges on the fin, are usually the sign of a disease, although there may be other causes.
In a healthy fish, the fins should visably stick out from the body. The one exception is the dorsal fin in some species.
A fish that clamps it's fins, and maybe rocks from side to side is definatly not feeling well, and may easily get a disease.
Eyes: The eyes should appear clear, and never protrude un-natuarally from the head.
Skin: The skin should not show any white spots, mold, fungus, or white film. The scales should hug the body, and look smooth. Be sure to examine the tip of the mouth with extra care, to be sure there is no white film.
Another sign to look out for when buying healthy fish is avoid it if it seems to hang around on its own near the bottom of the tank alot as this is a common sign of a sick fish. Also avoid getting a female livebearer that is heavily pregnant(although this can be hard to find, particurally in guppys) because not only is the move from the fish shop to your tank twice as stressful (i.e she will be more likely to abort her fry, become ill and/or die). The other reason is if there is a sudden difference in water stats like ammonia in coming from the lfs tank water to yours, this can cause birth deformitys in the fry, cause still born fry and/or miscarriages.
If there are sick fish in a tank, even if there are healthy ones in the tank, avoid buying fish from that tank altogether as the chances are that the "healthy" fish are already infected with the desease but have not begun to show symtoms.