OK so, when making a circle, you want it make it round.
Start with your top:
..................¸‹•^*º°ˆ¨¨¨¨¨ˆ°º*^•›¸
Now, you want your next part to be near-flat.
..................¸‹•^*º°ˆ¨¨¨¨¨ˆ°º*^•›¸
...............,-'...............................'-,
Now, the next part is a little steeper:
..................¸‹•^*º°ˆ¨¨¨¨¨ˆ°º*^•›¸
...............,-'..............................'-,
.............,'.....................................',
Now the steepest:
..................¸‹•^*º°ˆ¨¨¨¨¨ˆ°º*^•›¸
...............,-'..............................'-,
.............,'.....................................',
............;........................................;
Now repeat the steeping process. This is like mirroring but vertically:
..................¸‹•^*º°ˆ¨¨¨¨¨ˆ°º*^•›¸
...............,-'..............................'-,
.............,'.....................................',
............;........................................;
............',......................................,'
.............'-,................................,-'
.................`¬•-...,,,¸¸¸¸,,,...-•¬´
Just my two cents for ya.