What requirements must I meet to apply for a mortgage?

Banks use an equation in a triangle that covers the three main factors involving personal economy and housing prices, which are crucial to our ability to borrow: Income, Equity and Credit.

What requirements must I meet to apply for a mortgage?
Income: the rest of the relationship between what you earn (your actual income and taxable) and the total amount paid in respect of accumulated debts. Is measured monthly, and describes positive mind (from less than the amount that you leave your monthly debts, you are less attractive for the bank as a client).

Equity: Loan to value, a factor which measures the risk to the bank to lend money to purchase a property, and involves some fun facts:
The value of the home you’re buying (selling price) is not the same as its actual price (valuation) is possible through a mortgage to buy a house priced at 120,000 euros which is only valued at 90,000. The Loan to Value is measured by dividing the actual price of housing for the requested amount of the mortgage: a mortgage of 80,000 euros to buy a 120,000 house valued at 100,000, will have an 80% LTV, the higher the percentage, the greater the risk that the bank runs.
The devaluation of the real price of housing in Spain has meant that many mortgages have an LTV of more than 100%. That is, homes whose sale does not cover the loan amount.

Credit: The character of your history of credit from consulting, patterns of debtors and other sources that use banks