The techniques described here on the site are numerous, but the best thing to understand about the Third Eye is to also understand how it works in relation to the other chakras and how they are used.
I would start their, develop your understanding and look into your own methods. The pre-established methods are great and can be of great help, but especially with the Third Eye, our minds and thoughts work in different ways. Finding how your mind works and how it can best visualize the Third Eye opening, will probably work best for you.
However, fair warning, the first time you successfully open the Third Eye is often very jarring. You may recieve a wealth of insight or spiritual development from doing so, which is why it's recommended to understand and work on the other chakras first to get a feel for what happens when you open a chakra.