There is nothing like “negotiating” for a loan from a Bank. I dunno what you had in mind when you asked this question. Banks have given set of norms for any loan. Based on your credentials, your requirement, Bank will consider the loan on merits as per your eligibility. You have not made it clear what kind of loan you are talking about.
If you are asking for a personal loan (they carry higher rate of interest), it is based on your monthly income and I tell you, to the Bank Income is always what you have declared in your IT Return, last 3 years average will determine your avearage annual income which forms the basis for loan.
If you are asking for an Edu loan it is based on your rankings in your qualifying Exam and the amount of loan depends on the total cost of project - here it may be graduation or Post Graduation whatever.
If you are asking for a business loan your last 3 years Balance Sheets speak about you and your eligibility. I always used to advise my bank customers to have the balance sheets that reflect their business instead of underplaying to avoid taxes or whatever. In times of need you tend to lose if you need some Bank finance.
And finally coming to your “negotiation” part, I presume you are asking for a better rate of interest. Banks have already started implementing “differential rares of interest” to different individuals based on your ratings. Every Bank has a model of questionare and based on the data you provide, every question will be given marks- predetermined. This will decide your “rating” which will decide the rate of interest.
Please don't be under the impression if you negotiate, you will get loans on better terms- not so,atleast from PSU Banks.