These are the common things you first need.
Credit Report to all 3 bereaus
Taxes for the last 4 years ( 3 yrs is fine but better 4 years)
Pay stubs for the last 6 months
Bank Statements for the last 6 months
" ALL" Bills
House papers
Car notes
School Loan if you have one
Property taxes
Owede Goverrnment Taxes
Copy of Government Issued Identification such as Driver license ( I am from California)
so DL or California Id
Copy of social security or ITIN Number
Credit counseling
If debtors are filing jointly documents are needed for each debtor.

Note: I am not a lawyer, But I do BK
These are the thing i asked from my client.
In order to determine if you are eligible to a certain chapter like 7 or 13 u must take the means test.
And hopefully to meet the median income allowance of your state.
Its a given information already that you should take credit counseling before filing the petition.
A lot of things to do..
Any Questions feel free to ask.

Shared secret: I mostly learned from here before i get this job. and from reading books, and checking old cases from the office.
Now i do good thanks to determination