Ground cinnamon is very safe, the volatile oils can however cause a skin rash. Small amounts of coumarin can be found in Cassia and other cinnamons, generally only large doses of this compound will cause blood-thinning and liver problems, but it's something to be aware of. Also if you're planning on having surgery you should stop the use of cinnamon at least one week before going in as it has a blood thinning effect. You should also take care to monitor your blood sugar to avoid an unsafe drop in blood pressure.
The most common uses for Aloe would have to be for treating burns, wounds and skin conditions. This along with the ease of growing an Aloe plant make it an excellent choice to have in your herbal first aid kit. The real magic of the Aloe Vera plant comes from the gel inside the leaves, to extract this all you need to do is take a knife and take off the thick skin on the outside of the leaf. The part you're after is the clear inner gel, sometimes referred to as the inner fillet, because you're sort of filleting the leaf. When used on minor burns you should run the affected area under cool water for about ten minutes before applying the Aloe gel. Continue to apply the gel several times per day for both burns and skin conditions. If you're using the Aloe gel for lowering blood sugar levels take about one tablespoon daily (be sure to use an aloe gel that's free of aloin if taking orally).
As you might expect from an herb like basil it has a pretty profound effect on the digestive system and therefore works great for treating things like indigestion, bloating, and gas. When you're using basil to treat these problems I'd recommend taking around 2-4 grams per day taken orally. Basil can also be used to ease the effects of insect bites and stings, simply crush the leaves so the juices can be applied to the affected area. To help from getting bit or stung in the first place you can rub the juice on the skin in the same manner, basil works rather well as an insecticide so this should help repel the bugs.
The aptly named bitter melon is thought to help cells use glucose more effectively and block sugar absorption in the intestine. When Philippine researchers had men and women take bitter melon in capsule form for three months, they had slight, but consistently, lower blood sugar than those taking a placebo. Gastrointestinal problems are possible side effects. You can reverse diabetes with these science-backed strategies.