Sneak if you are mainly an archer.
Also, if you are already at 100 Archery or so,you should be around your late teens. So you will need to get sneaky to avoid melee. You don't have the skills or equipment to keep up with NPC that will come at you.
Next to it, I would level Light armor also, so you can withstand a little bit more damage. If you are sneaky enough, it shouldn't be that necessary. But if you are not familiar yet with how to sneak effectively, you will get detected pretty often and will have to somehow melee your way out.
Don't forget one thing: you can bash with your bow: it will do nearly no damage but will stagger your opponent so you can get away and fire an arrow at him on a short distance.