without meaning to offend, i'd just like to offer that isometric art can be very difficult for a pixelart beginner, or someone who has no worked with projections before. An understanding of form and volume and point of view is simply a prerequisit. I'm not saying you cannot handle it, but the basic concepts - horizontal and vertical distortion and three-dimensions represented on a two-dimensional surface, smooth representations of strangely angled lines and curves etc...they dont seem to be "there" for you just yet, not if you are asking questions at this stage.
Because isometric is so tedious for those who have a grasp of it, i would strongly urge you to hold off and practice other methods before sinking a lot of time into an isometric project that may not turn out the way you like. If you do want to go into isometric right now, i would say jump in head-long and don't ask - discover - you'll learn a lot more about it if you recognize the underlying principles of why a perceived square seen at an angle cannot fill a perfect square.