Your parents need to show some strong home ties, else if they do not mention anything about home ties they risk a refusal.
Attach (english translated version) the property documents. In my case i attached my mothers farm land documents.
Do your parents receive pension or are they part of any welfare community, etc ? If yes do mention same.
Do they have some home loan, car loan etc ?
Do not purchase flight tickets before getting visa approval.
I applied my mothers visitor visa few months back and it got approved. I attached below documents also:
1. Day to day itinerary; just create three columns in Excel; Date, Plan and Expense. for each day or for a range of few days, fill the columns and corresponding expense. It can be like - Day 1 - arriving in Canada and taking rest at home. Day 2 - going to shoping with family, expense - CAD 400, etc etc
Have a rough expense for each column and then the total. Your parents need to have min this amount of money in there account.
2. Have as many documents related to home ties as possible,
3. Be very specific about the Purpose of Visit. In my case, i only mentioned that my mother wants to come to Canada to meet her family and some sight seeing with exact site name like CN Tower.
4. In my case i also bought a travel insurance for my mother and attached same in application stating that her travel insurance would cover any emergency expenses.
Also 6 months is a very long time for a visitor visa, it shows that your parents have very weak ties to home country. You need to plan for say a months visa, have a very specific purpose of visit, have a travel plan and attach same.
