I would expand on one point above, which was also referenced in another thread: the name of the cabin you fly in
does not consistently relate to the points and Avios you earn - instead, the thing which determines this is the
selling class.
The authoritative source (though not 100% perfect) is the
Avios Flight Calculator page on the BA website. When you put in the airline, your BAEC level, the origin* and the destination* you get something like this:
The selling class is one of the capital letters in the brackets.
You'll notice that looking just at "Business" doen't give you the whole story: in this example, a ticket sold as "I" would only earn 750 Avios while the same route, seat etc. sold as "J" would earn 1250.
Even more importantly, to climb the status ladder it's the Tier Points (fondly known as "TPs") which count, so in the example above a flexible Economy ticket (sold as "Y", "B" or "H") would earn you
4x the Avios and TPs of the cheapest one (sold as "Q", "O", or "G").
On partners, the difference can be significant. On AA within the US for example (see below), many flights have a cabin called "First" but are exclusively sold as ("I", "J", "D" or "R") i.e. you will never get the "First" TPs (except on 2 specific routes) !!
The basic rule is to go by the selling class for each sector* (easy to see when using
ITA Matrix to plan travel) and ignore anything else !!
Finally, if the selling class does not appear in the calculator for airline/route you've selected (this happens on e.g. some MH tickets) then you risk getting
0 Avios and 0 TPs no matter how much your ticket cost...
That was a whistlestop tour - see the excellent threads linked above for the full story
* The calculator works on a sector basis so if you were flying e.g. from DUB to JFK via LHR, you would need to look up each sector (DUB-LHR and LHR-JFK) separately then add them togther.