HI, you have a good basic understanding so far.
What I would suggest is that with each oils safety data.
If you are using in a burner then really there are no real issues however if you are using in a way that the oils can absorb through the skin, that is compresses, baths, massage etc you need to be more careful.
Most oils are a bit difficult if you are diabetic because they mess around with hormones including insulin. There are a number which are best avoided if you have epilepsy, most notable is rosemary.
If you are pregnant, less than 16 weeks only use lavender or Mandarin, and stay away from oils that will stimulate your uterus right the way through the pregnancy, rose and jasmin being the main ones.
Look for the statement dermal irritant, that means it could burn your skin, pepper or citrus ones tend to have those warnings.
With the exception of lavender and tea tree make sure that you dilute all oils in something like a bit of vegetable oil before you put them on your skin.
You can get a chart with lots of data on from this site and also details on how best to use the oils.