Just some friendly reminders:
Remember to label the attached sheets as the instructions state.
Also, I started my application months before completing and submitting it and had to redo some forms and even photos as the forms had been updated by CIC and photo specs had also changed.
I included my proof of relationship usually as attached sheets and as responses to questions on the forms. My photo files were printed on regular paper and I typed captions and explanations on the pages also including them as attached sheets and responses to questions on the form. I did the same for any correspondence (email, skype logs, letters, cards, phone bills) and any boarding passes, ticket stubs etc. Personally, this helped me narrow down what and how much to send as proof of relationship. My relationship was long distance for several years so there was lots of travel, phone records, skype logs, and emails. I couldn't find anywhere on the CIC site or forms where it stated tabs could not be used so I put a tiny tab on each form so that they could be identified easily and clipped all the sponsor forms together and all the applicant forms together and put them in a document box purchased at the PO.