Starting with basenotes

When I started my perfumery training, I started by learning my smells. Learning the smell and behaviour of the raw materials that are used to create fragrances; and I started with synthetics as it is simpler that way. The smell and behaviour of a synthetic chemical is far less complex than that of an Essential Oil, as an oil is, in itself, a complex mixture of chemicals. An Essential Oil can be thought of as a natural fragrance.

I don't think it matters whether you start with all base notes, or all top notes or a mixture of all three types. You should follow the behaviour of the individual chemical over hours, and even days; you will soon find out whether a particular chemical is a tiop note or not.

From memory (and it is a long time ago) we started with about 20 chemicals. I'll try to remember what they were, in no particular order:-

Terpineol
Geraniol
Citronellol
Phenyl Ethyl Alcohol
Heliotropin
Coumarin
Vanillin
Linalol
Linalyl Acetate
Anisaldehyde
Cinnamic Aldehyde
Benzyl Acetate
Cinnamic Alcohol
Galaxolide
Hexyl Cinnamic ALdehyde
Hedione
Vertenex
Citral
Hexenol

I'm afraid I can't remember any others. They are a good start. Try to describe them in your own words, and it doesn't matter how daft the description. If that's what you think it smells like then that's fine. Only when you are familiar will all of thee should you refer to the "official" description. It takes time.

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PART TWO

Once you have become familiar with these materials and are happy that you know what they smell like. You can think about getting some more, and also getting some Essential Oils. Make notes. Do whatever it takes to become familiar. You can also start making simple mixtures to see what happens. It is all very exciting, and interesting. Enjoy.

Agree with David! Here in the EU, a part of the training I follow is to know the olfactory profile of the 26 perfume allergens that must be labeled as such. These are also important because many natural extracts contain them and they are used very often in perfume compositions.
Those allergens are:

Amyl cinnamal (CAS 122-40-7)\t
Anisyl alcohol (CAS No 105-13-5)
Benzyl alcohol (CAS No 100-51-6)\t
Benzyl cinnamate (CAS No 103-41-3)
Cinnamyl alcohol (CAS No 104-54-1)\t
Farnesol (CAS No 4602-84-0)
Citral (CAS No 5392-40-5)\t
2-(4-tert-Butylbenzyl) propionaldehyde = lilial (CAS No 80-54-6)
Eugenol (CAS No 97-53-0)\t
Linalool (CAS No 78-70-6)
Hydroxycitronellal (CAS No 107-75-5)\t
Benzyl benzoate (CAS No 120-51-4)
Isoeugenol (CAS No 97-54-1)\t
Citronellol (CAS No 106-22-9)
Amylcinnamyl alcohol (CAS No 101-85-9)\t
Hexyl cinnamaldehyde (CAS No 101-86-0)
Benzyl salicylate (CAS No 118-58-1)\t
d-Limonene (CAS No 5989-27-5)
Cinnamal (CAS No 104-55-2)\t
Methyl heptine carbonate (CAS No 111-12-6)
Coumarin (CAS No 91-64-5)\t
3-Methyl-4-(2,6,6-tri-methyl-2-cyclohexen-1-yl)-3-buten-2-one = alpha-isomethyl ionone
(CAS No 127-51-5)
Geraniol (CAS No 106-24-1)\t
Oak moss and treemoss extract (CAS No 90028-68-55)
Hydroxy-methylpentylcyclohexenecarboxaldehyde = lyral (CAS No 31906-04-4)\t
Treemoss extract (CAS No 90028-67-4)

Also important are various kind of musks, especially to determine if you are anosmic to any.
David mentions Galaxolide, but there are many others for example:

Musk ketone (CAS 81-14-1)
Ambrettolide (CAS 7779-50-2)
Tonalide (CAS 1506-02-1)
Exaltolide (CAS 106-02-5)
Velvione (CAS 37609-25-9)
Ethylene Brassylate (CAS 105-95-3)
Muscone (CAS 541-91-3)
Habanolide (CAS 111879-80-2)
Cashmeran (CAS 33704-61-9)
Celestolide (CAS 13171-00-1)
Helvetolide (cas 141773-73-1)
Cosmone (CAS 259854-70-1)
Musk lactone (CAS 3391-83-1)

hth

I wanted to start slowly; there is time for all the others. And by the way, allergens only have to be labeled if they are above a certain level in the end product. Just because it is there doesn't mean it has to be labeled. Not all of the allergens are easily obtainable either.

I learn one a day most of the time. I feel I haven't accomplished anything if I miss a day. It is a wonderful journey. The main thing is to have fun at the same time. There is no rush. It is my favourite passion.

I have about five or six Frankincenses and they all smell different to each other. I expect that is why the chemicals are easier.

Do chemicals smell any different depending which manufacturer made them?

Mumsy, yes. The main component will be the same but the trace impurities will be different. Also, possibly, the ratio of various isomers will be different. When you start learning about smelling stuff I always think that chemicals are easier because they are simpler (with a few exceptions, of course; there are always exceptions). Essential Oils and other extracts can contain hundreds of different chemicals all evaporating at different rates, all contributing to the overall ever changing smell. An natural perfume, if you like.

Not that I'm interested you understand.....

Of course not dear, of course not.

Good idea - I think the PA one is pretty good - is that the one you bought?

Take your time with each material: they often surprise in being different over time and of course you can try combinations by putting one material on one smelling strip and one on another and then smelling them together, which is very informative.