Greetings. First, this is my own view based, on personal study and experience.
To begin with, much is written on the 'right' colours for each of the chakras. People are encouraged to meditate with these colours as the goal. I have found that this is not necessarily the best way forward. In any chakra work, my suggestion would be first to work to discover what colours your own chakras already are. Then, do you really feel a need to change them? Why do we believe that everyone's throat chakra should be blue? Why not silver? Our chakras reflect our personalities, and our diversity is what makes us people. If a soldier's base chakra is deep red, is that not appropriate for who he is? Not all eyes have to be blue, so why do our chakras have to all be the same? (I would like to see some responses to this question).
Secondly. I question the wisdom in seeking to have chakras open. It looks like an exercise towards vulnerbility to me. Rather, I would seek to exercise flexibilty, that is, the ability to control whether or not a particular chakra is open or closed in a given situation. I certainly do not want my heart chakra open when there is furious negativity flying about the place. So, practice opening and closing at will.
There is a vertical spine of energy in our bodies, from above our crowns, going out at the base chakra between our legs. If you want to start chakra work, it is this that first needs working on, as it is the stem for all the chakras. Much like gardening, - if you don't look after the roots, the flowers will not flourish. You can start chakra stem work by breathing exercises. Stand up straight, bring an in-breath through your crown, and breath it out between your legs. Reverse this by breathing in from your root, and out hrough your crown. You will feel the effect straight away.
Lastly, I believe there are more than the traditional seven chakras. These are not nadis, they are chakras. My favourite is the chakras in our feet, - which we all know from grounding exercises. We also have chakras in our hands, - we know these from healing. Again, - my view.
So, find out for yourself the colours of your chakras. It is like cooking, there is no right or wrong way. If you are happy, keep it. If not, change it to suit yourself. None of us ever thrived from trying to be a person we are not.