In Path of Exile, there is much thought and time put into a character from the progression to the final build. There is a lot of freedom in a character's development due to the level of depth and flexibility afforded by the game. As the game gives you the chance to explore other options and come up with your own variation of a pre-existing build, you don't have to follow a character build guide to the letter.
This is something that the developers intend for their game to encourage at Grinding Gear Games, and as a Path of Exile player that's something you should take advantage of. You enter a wonderful and marvelously complex world of theorycrafting in Path of Exile, which is like a whole new can of worms exploded open right in front of your eyes. Whenever you pull up intimidating beautiful passive skill tree in the game, you have opened a Pandora's Box full of possibilities that theorycrafting will enable you to make the most of. You should consider PoE exalted orb and chaos orb for this build.
Basically, a more in-depth character build planning takes major aspects of the character into consideration. It's the process of fine-tuning a build based on game knowledge for the first time and research at hand basically, including the Path of Exile Items that either enhance or form the basis of the build. You have to plan ahead what class you are to have, what Ascendancy class you're aiming, as well as the offensive and defensive plans you have to rely on in the combat.
Most of the offensive and defensive plans are stat benchmarks that will ensure the character's overall effectiveness. In order to reach a minimum attack damage and speed or spell damage and casting speed will guarantee that you can deliver adequate damage to kill all kinds of enemies all the time. Making a certain percentage of armor, resistances, increased health and regeneration, you must be done to guarantee survivability, so even in the most intense of fights in the field you can still alive. You must consider the PoE Currency and skills that go into this build for those benchmarks.