The study of orchestral excerpts can provide a lifetime of enjoyment and it is so much easier than it used to be! There are a several handy resources you will want to explore.
WHICH EXCERPTS?
The graded excerpt list provided here will give you a starting place to learn the most common excerpts. Most of this is borrowed from a list Milt Stevens published several years ago.
WHERE DO I GET THE MUSIC?
Cherry-Classics.com offers a CD-ROM with all of the low brass parts for a large repertory of orchestral music (and other trombone music). You can just print the parts you need. I recommend this very highly. It is money well spent and will save you hours of trying to dig up parts from an orchestra library.
WHAT PART IS THE IMPORTANT EXCERPT? WHAT SHOULD IT SOUND LIKE?
TromboneExcerpts.org is a great resource. They provide the excerpt and several recordings of the excerpt with different orchestras. You can compare tempos and styles of different conductors and players. You will soon develop favorites.
As you become more advanced in your study of orchestral excerpts, you will want to own several recordings. I shop at amazon.com and can often find good used CD deals. If you are a college student, you should go to ruckus.com and get free downloads.
Learning the excerpt is just the beginning of really learning a piece. If you are a serious student, you will also study the full score to really learn the entire work and where your part fits in the big picture.
The ITA Journal has a column called “Orchestral Excerpts Class” where top professionals write about the major excerpts. Many of these are available online at ita-web.org. Of course if you are this interested in this topic you should be a member of ITA. Tell them DocSparrow sent you!