Have I mentioned that I was a teacher for 32 years? Oh, yeah, it's over there on the right side of the page. So what does teaching have to do with safety? Well, teachers tend to be hyper-vigilant about safety - maybe because we've seen a lot of crazy, unsafe stunts attempted by our students.
When I first started using essential oils, I thought they were 100% safe for everyone. My daughter had already been using them for a few years, and, except for Clove EO, she thought they were totally safe - even though she was a distributor for one of the major MLM's.
If you are new to EOs and/or herbs, if you never knew there could be safety issues with them, check out the Safety pages on this site. On those pages, I make recommendations for the safe use of essential oils and of herbs. My advice is based on all the studying and learning I've done over these past years.
Some of these cautions are irrefutable, i.e. certain essential oils are photo-toxic at certain dilution levels, others may be considered arguable. One very controversial advocation is that essential oils should be used externally only. There are those who believe that it's okay to ingest them, and some companies advise ingesting them. I'm not going to judge you if that is your belief. I will encourage you to research the topic thoroughly and make an informed decision on the controversial recommendations.
In my opinion, I've experienced that making an herbal tisane (tea), decoction, infusion, or tincture for ingestion is a safer alternative that is, in many cases, as effective as using an essential oil -- and combined with topical EO use can go a long way towards supporting the body.