Most people buy the packs in the order they were released in, to play the quests in order.
But you can buy any pack you like, or can get your hand on.
I bought SaF first for instance, the last AP of the dwarrowdelf cycle.
Why? Because I wanted Elrond, and that's it.
So my advice is to browse through the APs and select one you like for the player cards & quest.
Only for the AtS cycle will I recommend playing (not buying mind you) the quests in order for the story.
In the earlier quests the adventures do link, but on a far more shallow level, so IMO it's not that important.
So wait for a reprint, and buy some other pack is my advice.
has some great articles to get started on buying packs.
To browse the database on cards in a pack I recommend http://hallofbeorn.com