If you play saxophone, and someone asks you to play, and you don’t have music….. what are you going to do?
Even if you do call the ghostbusters, it’s not going to help you.
Knowing tunes and being able to make up a solo will save you.
Putting in the practice beforehand will help you out a lot. BUT you don’t want to sound like you’re practicing when you’re taking a solo. So part of it has to be spontaneous. If you put together phrases you know in a way that sounds good, you’re still being creative.
In that sense it’s like language, you speak using words and phrases. It’s not as if you make up new words on the spot using only the letters.
Above phrasing and ideas even, the most important thin however, in my opinion, is your sound. People will often compliment you afterward by saying, “you sounded good.” So practice your long tones! Those will make you sound better and more in tune.
It’s not just about sound though, you also don’t want your rhythm to be off, so practice with a metronome!