Don’t reflexively reach for EQ: If an instrument doesn’t sound right, try changing the source. Move the microphone, adjust the amp, or try different equipment. Small adjustments can make a big difference. And the less processing you need to do, the easier it’ll be to mix.
Have a goal in mind: With a plan in mind before you start recording, you’ll have a much better idea when you’ve captured the right take. As the saying goes, if you don’t know where you’re headed, how can you tell when you’ve arrived?!
Be comfortable: Whether you’re performing, recording, or mixing, you’ll fare better with fewer distractions. You don’t need concerns about heat or thirst throwing you off your game. If it’s hot, turn on the A/C (and if that’s too loud, just shut it off while the tape is running.) If you’re thirsty, especially while singing, drink lots of water. If you’re tired, take a break.