I would recommend going to a professional salon near where you live for a consultation with the colour technician.
Hair is a fragile fiber. Look at mine! Hair is dead which is why it needs care and attention. You are right to be concerned over mucking your hair up and a good hairdresser after a thorough consultation will be able to inform you of your options. Remember anything can be done but it is the condition and tone already in your hair that will definitely limit the options open to you. ...More >
Going lighter to a light brown actually means removing all the previously dark red tone you have had put in which can be done but this will affect the condition of your hair. So it is for these reasons that I think you must get a professional opinion they can see your hair first hand and advise you of how to achieve what you want without messing your hair up.
Once you have your achieved a colour you are happy with, it is important to give your hair TLC. Make sure you use a professional shampoo conditioner and treatments that your hairdresser will prescribe for you. And when styling ensure you use the right products to maintain and look after your hair condition.
If you straighten your hair then professional irons are the best by far as the infra red heat helps protect your hair by locking in moisture and the cuticle is left smooth and shiny and healthy which is vital to get the best colour result out of your hair. When you have had your hair coloured maintaining the colour is important to look after the investment you have put into your new hair colour and style.
Remember keep it on your head and not in a bag.