When learning a song, should I learn to play it in all 12 keys?
Not to start with. As a beginner, you should try to learn as many different jazz standards as possible. This way you will be exposed to a wide variety of different chords and voicings that would not have been possible from just learning 1 song.
As a beginner, it is a good exercise to transpose a song into maybe 1 or 2 different keys, however, it’s difficult and also very time consuming so your time would be better spent learning new songs to extend the size of your repertoire.
Should I learn one arrangement of a song and play it the same way every time?
One of the misconceptions with jazz is that everything is made up on the spot. This may be true for the improvised sections, but for the ‘head’ of the tune – which is the first and last time through – you will naturally create an arrangement. Sure, you can make slight tweaks, change the rhythm of certain melody notes, move things up/down an octave etc. This is all part of the performance!
Where can I take inspiration from when creating an arrangement?
Before you try to play a new jazz standard for the first time, listen to as many arrangements as possible. Use platforms such as YouTube and Spotify to find performances and recordings from both professional and amateur musicians.
Make note of anything you like and then try to incorporate this into your own arrangements.
Listening to vocal versions of the tunes you are learning is a great way to work on phrasing and also helps you understand the movement and contours in the melody.
Should I memorise the chord changes or just read from lead sheets?
You should definitely try to memorise the chord changes and form. This does come naturally from playing songs over and over. Always identify the common chord progressions such as 25s and 251s as this will help you with choosing suitable chord voicings and creating improvised licks and lines.