1) Use an X-Y chart (I think) - more control over x and y point.
2) Plot a few points in a data grid
3) charts always need tweaking until they look right. If you have many data points you can use a trend line, perhaps.
More on charts:
Sample Demand Curve:
(note: the headers for Qty and Price are in B10 and C10,
the qty data values are in $B11$:$B$15 and price data values are in $C$11:$C$15)
These are chart options for the above scatter (xy) chart: