With my iva company today and it has been brilliant and i honestly believe that this is the most important thing I have found so far!
I think talking to your company and getting all the info that you need is so important.
Now we talked it all through, they gave us all the info but as much as you try and take it all in when you are in the middle of the whole process it is hard.
So today i called them with a list of questions and got the nicest girl. I asked her all my questions, she gave me lots of answers and a lot of advise.
I think my problem was that i wanted to ensure that i was doing everything ok. I wanted to ensure that i was telling them everything when they wanted it. I didn't know if i needed to keep receipts etc.
So my tip, which i am sure you all already knew, is to talk to your company/IP and not to be afraid to ask questions!