'
The Silmarillion' should be read before 'Unfinished
Tales'. 'Unfinished Tales' contains some information that expands upon 'The Silmarillion'. (Narn i Hin
Húrin,
Tuor's journey to
Gondolin.)
'Unfinished Tales' is quite versatile. Not only do we get some
Second Age stories and it's main focus is on
Númenór, as well as the excellent collection of various essays or notes titled 'Of
Galadriel and
Celeborn'.
It also expands on the LoTR and 'The
Hobbit'. It contains several essays that were meant for the Appendix, and we get detailed accounts of the death of
Theoden's son Theodred and the Battle of Isen, the Hunt for
The Ring and we also get the background story to as how
Gandalf managed to persuade
Thorin to accept
Bilbo into the Quest of
Erebor. We also get several miscellaneous essays on the
Palantir, the
Istari and the
Druedain.
'The Letters of
Tolkien' can be read at any time. It is advisable that you do not read them in one go, it isn't the sort of book that you read at once. It is a brilliant reference though, filled with a lot of hidden gems of information.
You could also read 'The Adventures of
Tom Bombadil' (Tales of the Perilous
Realm) and various other tales of Tolkien, which either slightly link with
Middle-Earth (Roverandrom, Smith of Wooten Major) or not at all (Farmer Giles of Ham) though as with the Letters these can be read at any time.
The volume's of HoME that you are talking about (6-9, History of LoTR) deal with the development of LoTR. These can be read at any time, and if you are esp. interested in the development of the LoTR and different phases and ideas that Tolkien came up (there are a lot) then this would be a good read; but even if you find this boring (there is little 'new' information, though a lot of interesting information i.e.
Aragorn started out as a Hobbit) then never fear, for some interesting HoME
books are here. Or there. Whatever. The last part of HoME 9 deals with linguistics and Númenór. (The Notion Club Papers.)
There is a History of the Appendix in the first half of HoME 12, and there are several essays that deal with the F.A-T.A (Mostly based on the Silmarillion, the 'Shibboleth of
Fëanor is v. interesting if you are a
Noldor fanatic or 'Of
Dwarves and
Men' if you want to know about the history of Men and Dwarves (naturally) and some cool S.A information. (There is too little of that.) There is also the interesting story 'Tal-elmar' about some
wild men in the S.A and the negative effects of
Númenórean hegemony over M-E, and the only story set in the Fourth age-'The New Shadow'. Some of the essays in HoME 12 link in with essays in U.T. i.e. 'The Druedain' is lifted out of 'Of Dwarves and Men' and some parts of 'Of Galadriel and Celeborn' are from 'The Shibboleth of Fëanor'. We also get other essays, such as the 'Heirs of
Elendil', a slight expansion on the Appendix, the Dangweth Pengoloð, which amongst other things deals with
Lembas and the 'Problem of Ros'.
HoME 10 and 11, deal with Tolkien's post-LoTR Silmarillion work, and most of the 'Published Silmarillion' is lifted from these two volumes. (Tolkien never got around to finishing the Silmarillion so C.T had to use earlier versions found in HoME 4 and 5.) There are also several interesting essays/stories such as 'The Wanderings of Húrin' and 'Athrabeth
Finrod ah Andreth' and 'Myths Transformed' which is a series of essays on drastic changes Tolkien made to the mythology. HoME 10 and 11 contain some new info. on the Silmarillion as well as the background work to it.
HoME 1 and 2 the Book of Lost Tales chart the beginnings of Tolkien's mythological world, and tell us about the journey of
Ælfwine to Eressëa where he learnt about the history of
Ainur etc. and we get the beginnings of stories that latter appeared. (Gondolin, Flight of Noldor,
Beren and
Lúthien, Húrin’s family.) HoME 4 and 5 deal with Tolkien's expansion upon the Lost Tales and the creation of the Silmarillion. HoME 5 also has the beginnings of the Númenór legend in the abandoned story named 'The Lost Road'. HoME 3 is sort of a in between and contains poems on various things. (Húrin, Beren and Lúthien.)
Hope that's all.....
