Sorting of geographic coordinates

I have an excel file with X - Y coordinates. Plotting the file using the scatter plot, i get this:

Howerver, when I plot the same shape file (using the plot option), exported to excel, I get this:

Which is because my data is not arranged properly. How can I properly arrange/sort the excel file so i get something similar to the first image when i use the plot option?

[madhan ravi]

Try 'xk' as marker in plot function

[Darlington Mensah]

What i need to do is to sort my coordinates clockwise or anticlockwise such that i can get a defined polygon with the plot option. I do not seek to change the marker