Huge Django project
When I come to this kind of problem I open up a notebook and answer the following:
1. Infrastructure

Server configuration, OS etc
Check out the database type (mysql, postgres, nosql)
External APIS (e.g Facebook Connect)

2. Backend

Write a simple description
Write its input/output from user (try to be thorough; which fields are required and which aren't)
Write its FK and its relation to any other apps (and why)
List down each plugin the app is using. And for what purpose. For example in rails I'd write: 'gem will_paginate - To display guestbook app results on several pages' 

3. Frontend

Check out the JS framework
Check the main stylesheet files (for the template)
The main html/haml (etc) files for creating a new template based page.

When you are done doing that. I think you are much more prepared and able go deeper developing/debugging the app. Good luck.
I have a new job and a huge django project (15 apps, more than 30 loc). It's pretty hard to understand it's architecture from scratch. Are there any techniques to simplify my work in the beginning? sometimes it's even hard to understand where to find a form or a view that I need... thnx in advance.