Hmmm.. Let me think...
Don't assume that if you get one essential oil of a essential oil, say Frankincense, that all frankincense smells exactly that way.
In the beginning, I had people tell me that Frankincense lasts forever, So I thought it was a basenote. Then I got more types and different distillations, different extractions, fractional distillations, from different suppliers, from different countries, etc, etc, etc. They're all different. I once mentioned that some frankincense was more of a topnote, I got laughed at by an inexperienced member of the Yahoo Perfumemaking group that I moderate. But if you look at some Frank's GC/MS, Limonene is very high on the percentages, and Limonene is a topnote, and the lower notes in a distillation take more time to come out. So this topnote rich essential oil was a short duration distillation of Frankincense, instead a basenote weighted Frank that was distilled over a longer time...
Don't buy a ton of a single citrus oil at once, buy small amounts, and replace them once a year.
At your very first opportunity, buy this scale, and only blend according to weight, instead of drops.
And MOST IMPORTANTLY!!!
WRITE EVERYTHING THAT YOU DO DOWN SOMEHOW - SOMEWHERE - SOMEWAY - ANYWAY ! ! !
Even bad notes are better than no notes
Don't think, Oh, This is just a scribble, it's not important... it won't matter. Write it down...
Using a spreadsheet is ideal. Ask around, there are a couple of them.
Don't believe those yahoos on the internet who say to add glycerin to your fragrance.
Don't mix carrier oils and alcohol, nor oils and water
Look it up on TGSC First...
Get over being stupid
Get ready to spend a lot of money.
Get ready to Waste a lot of money.
Get ready to spend a lot of time.
Get ready to Waste a lot of time.
Get ready for failure (s) time and time again. and again. and AGAIN.
Don't be convinced that you can make a commercial level fragrance before you spend at least five years learning, more likely 10.
Don't be afraid to give up and move on with your life if you really aren't very good, because you just can't keep pouring money into a hobby that will consume all of your extra time and money.
Don't forget the people in your life. Make them perfume(s) repeatedly, even if they're bad.
Don't get upset if they won't wear it or laugh at you because it actually stinks...
Oh, that's enough for now, plus my wife is calling... and I have to make Dinner with two hungry boys to feed...