Ash24: you ask "where does one start?"
Perhaps you are talking specifically about Listener 3951, but I'll choose to interpret your question as requesting general advice for newcomers to "advanced thematic" puzzles like Listener, EV, Inquisitor.
May I suggest:
1) Solving clues is often easier than understanding the preamble! Do read the preamble carefully, but if it is confusing, don't worry - go straight to solving the clues. All may become clearer later on.
2) Even the hardest puzzles have some easier clue types like hidden words and anagrams and these can provide a reasonably straightforward start. However...
3) ...many of the words used are rare, so equip yourself with appropriate solving aids. Chambers dictionary (preferably the CD-ROM) is essential. Bradford's Crossword Dictionary is very useful, as is the computer program TEA, available from
http://www.crosswordman.com/
If you'd prefer not to spend money buying the above, the sites at
http://www.onelook.com/ and
http://www.chambersharrap.co.uk/chambers/wordg ames/word_wizards/wwizards.py/main
are vastly better than nothing. Beginners should allow themselves free use of such aids. More advanced solvers may take pride in solving puzles without.
4) There are a few types of non-standard clue which regularly appear, such as clues containing extra words, misprints, or where the word-play leads to the answer plus one extra letter (or missing one letter). These can be intimidating at first. You may find it helpful to get hold of the Chambers Crossword Manual by Don Manley, which explains "advanced" and "special" clue types.
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