"In studio focus on the goal of the job, try to figure out exactly what needs to be done and do it effectively. Studio time is precious."

Especially if you and your band managed to scrape together enough cash for a demo - make sure you discuss what you are going to play ahead of time with the engineer/producer, and then practice, practice practice to get it perfect in the studio!

Studio time is not only precious, it can be damn expensive, so make sure you are well prepared. Rehearse as a band, rehearse alone, make sure you can really play your parts.

This is what I meant as well, only I used the wrong word. Precious means pricey here as well, like something valuable (in material)

This is an important tip. Also there is the ultimate lie "We'll fix it in the mix" - so don't rely on that rather practice all the parts and bits and enter the studio only when the whole band is ready to record their parts well and efficient.

Also I think if you are pretty confident on what you are going to record is going to come out more natural and sound better than doing it for x number of takes.

I may add to this that a "perfect" take doesn't always has to be perfectly played. Sometimes, the best take is full with emotion but not played "the best"