I posted this list on other forum for starters:
There are no sticky threads on common issues here I'm not a moderator to make one, but here's the docs needed in the most common scenarios:
1. Color copies of all you passports pages-- at least covering relevant 4 year period + the current one, even if it was renewed after application, with stamp translations (I wouldn't bother to translate simple self-describing stamps), plus the table with references to the stamps in the passport pages with dates on stamps, country and entry/exit direction is good to have.
2. CBSA-- there's a consent in RQ form, so you don't need to provide one to CIC, however you may want to request it for yourself for verification. It may take 30 days or more to get report. Plus you may need to specify you need highway passage report, which is for car crossings, based on car license plates.
3. US CBP-- not generally required, but won't hurt, if you're frequent traveler to the US and have US visas. You can request it electronically. The problem with this report is that CBP is currently backlogged, so it may take several months to receive it (my request took 11 months, highly recommend to try request expedited processing).
4. Copies of your travel tickets, boarding passes, reservations and itineraries.
5. T4, T4A, T5 and similar forms plus CRA notices of assessment (NOA's) (very important!).
6. Rental agreements, rental receipts or cheques, or mortgage documents.
7. School records-- attendance letter with dates attended, courses and hours, attendance tables and transcripts.
8. Letters of employments and records of employment (ROE's), if available.
9. Medical history (check out eileen's site, below).
10. Driving records, vehicle registration info and auto insurance records-- from your provincial licensing/insurance company.
11. May be much more-- if you have your own business in Canada, children activities etc.-- see sections in RQ form.
12. I would also submit credit card or bank statements showing account activities, with indication of who is the primary holder.
Though there are examples of documents to provide in RQ form, the list is not exhaustive. You have to demonstrate you have had presence and activities in Canada during the period and it depends on your situation.
Also check out eileen's site: http://residencequestionnaire.wordpress.com/