At some point you'll find yourself working with other musicians who many not be up to you level. It's important to remain supportive to them while still getting the job done. Here's my guide…
Whether it is part of a band situation or a jam/open mic scenario, working with less competent musicians is an important skill to learn – and one you need to master with tolerance and positivity.
Don't expect too much
If you've found yourself getting angry or frustrated with the musicians who are less capable than yourself, remember they look to you for guidance and advice. You were once like them and they appreciate the knowledge you can impart. Giving them shit for not being good (a situation they are working on improving) doesn't help anyone – and just gives you a repuation for being an ass.
Instead lower your expectations. Don't assume they know what you know. Spell it out for them in simple language.
Be prepared to take the lead
It's likely that you have more experience than they do, so use that to your advantage. Take control of the rehearsal and guide the other players. Became the musical director and manage the proceedings, including gentle prods "Let's stay focused, we can talk about that chic from last Friday after" and praise "That was great. Can you feel that its so much better than the first time you played it?"
Also, manage the players while they are playing: call out the section changes "now to the middle 8" and be prepared to stop proceedings and recap should anything be unclear.
Make it easy for them to move forward
If they are struggling with a particular part, simplify it.
You'll all get more done by omitting a few notes rather than wasting time while they attempt to nail the full part. Remember: Getting a whole song ticked off as done is more important than absolute mastery of 16 notes before verse 2.
Later on, once the simplified version is mastered, attempts at the full intricacy can occur.
If there’s a signature part, tab it out for them.
Very recently I was working with a bass player on a riff based song. The entire song hung on the repeated execution of the riff but somehow he'd not quite gotten the correct notes (a semitone out in places).
When he realised he hadn't got it down he said "I'll work on that for next time." But I had another idea.
Instead of berating him for not having the part down, I simply wrote out the riff in bass tab. This meant that we could continue working on the song that night, rather than having to wait a week.
Give these guys any tools you can so you can all move forward immediately.
Have (your own) clear understanding of the arrangement
If you don't how many choruses before the end of the song, then its likely they don't either. Making notes on song arrangements (or charting the song) prior to rehearsal gives you clarity but also provides rock solid info to them (which you can share/copy)
Once you have the original artist arrangement clear for all band members, then you might decide to re-arrange it or tweak it but be sure to document them.
Allow extra rehearsal time and limit the number of songs
With stops for errors, questions and part-writing you'll need more time to get the same amount done. I like to limit the number of songs to rehearse to 4 per 2 hour session. That's 30 mins per song. Having fewer songs to go through means a more focused and deeper dive into each song rather than skimming over the top. And this way, even the most forgetful player eventually "gets it" in the time allotted.
Document the correct run-through
Getting an audio recording of the band playing the agreed arrangment error free - however rough - is valuable as it can be distributed to all band members for their reference and to solidify their recall and unstanding of the arrangement post-practice.
There's nothing worse than getting good versions of arrangement at one practice, only to have to start again the next week because everyone has forgotten what they did.
Don’t be afraid to discard
If something really isn't working then be ok with jettisoning it from the set and finding a replacement. The torture of grinding through 17 takes of Sweet Child O’ Mine, lessens its appeal somewhat!