Here is what I was taught, at first try and stay off the busier streets as much as possible, even if it means you'll have to go a bit out of your way, you won't have as much traffic to deal with, which should make things a little less stressful, if you do have to drive on a busy street then get into the lane you need to be in right away and don't change, no matter how slow traffic is moving, also make sure you give yourself a little extra time to get to where you are going, if driving already stresses you out, you don't need to add the anxiety of being late to the equation, also until you get comfortable, don't drive with a passenger if you can help it
and as my dad always told me, "Drive with the mind set that everyone else on the road is a fucking ******, and don't know what they are doing, cause there is a good chance they don't"
over time you'll get more comfortable and confident behind the wheel, it just takes time and practice