Low Poly Modelling

Having ordered The main source for my project (3ds Max Modelling for Games: Insider's Guide to Game Character, Vehicle, and Environment Modelling: Volume I: 1. Written by Andrew Gahan). Ive started testing my skills at low poly modelling by starting a design for Piranesi's Arco di Gallieno drawing whilst waiting for the book in the post. having never having to low poly before jhopefully i will elarn new techniques by creating this piece and eventually transforming it and importing it into Unity game engine and possibly a level editor 

Here's just a quick image of my model so far and the Arco di Gallieno by Piranesi for comparison...

Here is the Original piece by Piranesi