When designing your character, keep in mind some simple rules for figuring out human proportions. Proportions refer to teh ratio between the height, width and depth of an object. Of course, these are just guidelines, but it is good to start here and then exaggerate as desired.
Before you start drawing, sketch you the proportions, but using the head as a guide.
An average adult is usually between 7.5 and 8 heads tall (including the head itself).
Below are some guides you can use for working on your image planes.
Remember--Your character needs to be modeled in a T-pose, with arms straight out from the body and palms facing down.
From the side Orthographic View, you can leave the arms off... (https://www.pinterest.com/pin/470204017323076505/)
A tutorial on Image Planes can be found in a separate tutorial page on the CS22.me website.
The purpose of this page is to give you some guides for proportions. For more on character proportions, you can visit anatomy4sculptors.com. They charge for many of their services and sites, but you can see some of their stuff for free.