Its no secret chief gear and charms are of vital importance to power. Here is some helpful information for you.
The most common rule is to make sure that your Chief gear stays close to the same levels. Your infantry levels should be 1 level above lancer and marksmen. This is the common agreed upon strategy throughout all states in WoS.
The graphics above show the needed materials to bring your gear up. Also, there is a trade shop that appears at mythic stages. If you get one piece to mythic first, you can then start trading out items that you have excess of to help speed up the remaining process.