How do i bake cookies in a gas oven without burning the bottom and end up with a pale top?

Consider getting some of the airbake cookie sheets - it's essentially like 2 cookie sheets stacked so there's an insulating layer of air between them.

Make sure your cookie sheet is not too big for your oven. Must have plenty of room for heat circulation. Check you oven temperature with a thermometer.

Place your oven rack in the upper third of the oven, and if you have more than one cookie sheet, stack them, so the bottoms don't burn.