Agree on a setlist before you arrive so rehearsal time goes toward playing together rather than deciding what to play, since figuring out songs on the spot wastes the limited time a group is together. Run through the hardest transition or section of a song slowly and repeatedly rather than always starting from the beginning, since playing the whole song end to end each time means the tricky part gets the least practice. Use a metronome or click track when a song keeps speeding up or dragging, since a group naturally shifts tempo together without noticing, and an external beat catches this before it becomes a habit. Keep the volume low enough that everyone can hear each other clearly, since a mix where instruments are drowning each other out makes it impossible to catch timing or pitch mistakes. Record a rough audio or video clip of a run-through and listen back together, since problems that are hard to notice while playing are often obvious once you hear the recording. Take short breaks between long songs or sections, since fatigue quietly causes sloppy timing and missed notes well before anyone feels tired enough to say so.