It’s a good idea when baking pretty much anything to rotate the item about halfway through baking to even cooking and browning. One trick is to rotate about 60% of the way through the baking time instead of 50%. Browning usually takes place toward the end of the baking (if you’re baking at the correct temperature), so rotating later will ensure a more even browning.
When baking biscotti, it is helpful to slightly underbake the logs on the first bake to enable easier slicing. The perfect time to take the biscotti out is right after they begin to firm up and colour. Once sliced, dry the biscotti at a very low temperature; around 225F. It will take longer, but you’ll end up with a more evenly dried and coloured and product.