How to Find the Most Stable Conformation of Cyclohexane
The first step in drawing the most stable conformation of cyclohexane is to determine — based on whether the substituents are cis or trans to one another, and based on where they’re located on the ring — what the choices of axial and equatorial positions are for the substituents. A handy way of determining the substitution alternatives is to use the Haworth projection, as shown here.
This projection is easy to make — simply start at some position on the ring and alternate axial (a) and equatorial (e) from carbon to carbon, and from top to bottom. This projection will tell you what the two options for the two-chair conformations are.
For example, if you were asked to draw the most stable conformation of cis-1,3-dimethylcyclohexane, both substituents could be on the top of the ring or both could be on the bottom of the ring, as shown here. (Recall that cis means that both substituents are on the same side of the ring.) As the figure shows, to get the cis stereochemistry, either both of the substituents could be equatorial (both e) or both could be axial (both a).