Before you start working on the reed crow it, play it and think about these things:

RESISTANCE — Is the reed so hard that you are biting to get a sound? is it so easy that you have to resist any embouchure pressure at all? At either end of the spectrum you’ll find you tire quickly. I actually find that a reed that requires no embouchure is more tiring than one that requires a bit too much pressure.
RESPONSE — When playing as softly as you are able, does the reed still respond? Remember that a reed with a great sound but lousy response is useless!
STABILITY — Play a long tone and crescendo and then decrescendo. Does the reed maintain its pitch (understanding, of course, that you have to balance embouchure against air speed). Play some scales and play ‘em loudly — is the reed misbehaving wildly? A wild reed can drive an oboist nuts (if he or she isn’t already there!).
TONE — Of course you want a good sound! Who doesn’t? But take my advice and record yourself on a few different reeds … you won’t hear nearly the amount of difference as you think you might. It’s quite surprising. So we aren’t talking about tone quality here, which is subjective anyway, but you don’t want a reed that only has high partials, and a reed with low partials which can sound pretty darn dead.

So … analyze that reed!

If the reed is too easy and is sharp, you are probably too late; you’ve taken off too much cane.

If the reed is hard and sharp you need to remove more cane. This will lower the pitch and will also make the reed easier. You can thin the tip (carefully!), thin the sides of the heart, thin the back, and thin the spine and middle of the heart. Do one thing at at time, on all four quadrants. Work slowly. Just a few scrapes and try that reed again!

If the reed is flat clip the tip. This will bring the pitch up, but it will also make the reed harder.

If the reed is too bright lengthen the blend, scrape the heart, scape the back, and/or clip the tip. Remember to do all of this slowly and carefully … especially the heart! (I, in fact, skip the heart most of the time.)

If the reed is too dark (yes, that can happen!) lengthen the tip. This is challenging, since you’ve already set the reed up. Scrape more wood from the heart (and less wood from the back the next time you work on a reed).

If the reed is too open you may have soaked it too long, or you may have to remove more cane. If it’s just that the reed is simply too open you can try to close it a bit by soaking it and then hold the reed shut between your thumb and forefinger for a minute or so.

If the reed is too closed you need to soak it longer. Most likely, though, it is old and should be tossed, or the diameter of the tube was too large and the cane was bad anyway. When I have an old reed that I’m hoping to resurrect for just a short amount of time I soak it in extremely hot water for a minute. Sometimes that brings a reed to life for enough time to get me through in an emergency.

If the reed leaks you simply need to wrap a bit of parafilm or fishskin around the reed. Try to put on as little as possible and don’t put it too near the tip.

Remember:

As you remove cane the pitch drops.

Keep the spine intact and don’t carve those rails!

Always use caution when you are working on the heart. There’s a reason we call it a heart!

Avoid creating nicks in the tip and heart. They prevent the reed from vibrating from the very tip, through the blend and heart and down to the back. Nicks in the back aren’t a problem.

The tip should be thicker in the center than at the edges.

And about that knife: sharpen, sharpen, sharpen!