just go slow and listen to your body. too often people start off too hard and then burn out and quit.
also, write everything down. this is especially helpful when starting out as it will help you know what weight to work with. spend the first couple weeks trying different weights until you find the amount that you are barely able to perform the final rep with. and if you aren't sore the next day from it, raise the amount when you go back. the amount will go up quickly at first and then plateau. after 2 months then stop lifting for a full week to really allow your body time to heal. you will be amazed at the change when you get back in the gym.
also, write everything down. this is especially helpful when starting out as it will help you know what weight to work with. spend the first couple weeks trying different weights until you find the amount that you are barely able to perform the final rep with. and if you aren't sore the next day from it, raise the amount when you go back. the amount will go up quickly at first and then plateau. after 2 months then stop lifting for a full week to really allow your body time to heal. you will be amazed at the change when you get back in the gym.