Many first-time buyers make the mistake of finding a house first, writes Laura Slattery.

When thoughts turn to buying your first home, a picture emerges of a dream home, surrounded by the Irish equivalent of a white picket fence and fully decorated with all the interior finishings that money (and taste) can buy.

It's when first-time buyers try to convert fantasy into reality that they usually run headfirst into a few brick walls.

As a property ladder novice going down this path for the first time, the chances are you won't quite know what you're doing. You may know what you want, but the technical details of how to get it are still surprising.

"Teasing themselves" by looking at properties they can't afford to buy is common among potential first-time buyers, according to Mr Paul O'Neill, a financial adviser based in Midleton, Co Cork.

"Sometimes they come to you and say: 'I've found a house. Now how can I go about buying it?' They're doing it the wrong way around," he says.

"But emotions take over and it's a case of heart over head. They will tell you that 'that's the house of my dreams, I'll do anything to live in that house', and they forget how they're going to pay for it."

Mortgage adviser Ms Sarah Wellband, of broker REA, says that getting the order wrong is the most frequent mistake first-time buyers make.

"They should always start with finding out how much they can borrow and get a written approval in principle from a lender - either via a broker or direct - before they start looking," she says.

So it is time to stop spending weekend afternoons driving around strange neighbourhoods and examining floor plans, and instead start getting your head around the scarily alien financial details.

Looking longingly into estate agents' window displays is one thing, but trying to negotiate the mortgage maze is altogether more disorientating.

The first step to buying a property is finding a way to fund the deposit. The maximum amount mortgage lenders will advance to almost all buyers is 92 per cent of the purchase price of the property. This means the other 8 per cent has to come from somewhere else, whether it is from parents' bank accounts, the credit union, or your own painfully accrued savings.

Once the deposit is in hand, the next step is to collate the necessary crumpled bits of paper that have been stuffed away in your important documents drawer, gathering dust.

Buyers are often surprised by the amount of paperwork they need to present to lenders before they will be fully approved for a mortgage, according to Mr Ronan Mackey, new business executive at NC Mortgage Brokers.

"No one in this day and age thinks they have to bring in a P60 and get their boss to sign off on a salary certificate and get photocopies of their passport, and it's partly because you can go in and get a car loan from a dealer in five minutes flat," says Mr Mackey.

"People resent it in some way, but there has to be a way of proving your financial circumstances."

So what documents will you and any co-buyers have to gather together? This may vary depending on the lender and your circumstances but, in general, it will include payslips for the past three months, your P60 and a salary certificate. You will also need details of existing loans (i.e. car loan statements going back about 12 months), current account statements for six months, photo ID such as a passport or driving licence, and a utility bill.

Self-employed people will also need to show their accounts, generally for the past three years.

The second step is to do some research: don't just walk into your nearest bank or building society expecting frank, unbiased advice followed by a good deal.

"The majority of first-time buyers go into their local branch on the assumption that their bank will sort them out," says Mr O'Neill. Some borrowers who get a mortgage this way don't even know what interest rate they are paying, because it hasn't been explained to them, he says.

"First-time buyers need hand-holding, but they might be a small bit cautious about going to an independent adviser," says Mr O'Neill. "They don't know what brokers do."

According to Mr Tice O'Sullivan, financial adviser at online broker Primafinance.ie, first-time buyers sometimes think that if they go through a mortgage broker they will pay more.

"Most mortgage brokers work on a commission basis and will secure the customer the same rate that they would get if they went to the bank themselves," Mr O'Sullivan says.

Even if you don't go to a broker, it is essential to talk to a broad range of lenders.

"Many first-time buyers get so excited that a lender, any lender, will offer them a mortgage amount they need to buy their home that they fail to ask the hard questions such as 'would another lender also offer me the required amount but at a more competitive rate?' " according to Mr Liam Ferguson, who is managing director of intermediary Ferguson & Associates.

Getting a mortgage is, after all, the biggest financial decision many people will make in their lives.

"It sounds crude but you don't necessarily marry the first person you sleep with so you don't always take the mortgage from the first lender who offers you one," says Mr Mackey.

Each lender has its own way of calculating how much it will advance to a first-time buyer and, with property prices escalating out of many buyers' reach, finding the most generous lender could mean the difference between becoming a homeowner and paying rent indefinitely.

First-time buyers often assume that lenders still use the old income multiples of four-and-a-half times salary (in the case of a single borrower).

"That is no longer the case as banks use a combination of income multiples and net disposable income to determine affordability," says Mr O'Sullivan.

This means that a lender might advance a mortgage where the repayments do not exceed 35 per cent of the borrower's net disposable income. Some lenders, however, will go up to 40-45 per cent under certain conditions.

One lender might be good for a particular salary range, say €25,000-€35,000, while another might tend to lend more than its rivals to a couple earning a combined salary of €75,000. Lenders will also have varying attitudes to income earned from bonuses, overtime and commission.

But buyers should remember that lenders don't always take the full value of bonuses, overtime and commission into consideration when making their calculations.

Although lenders will do "stress tests" to make sure first-time buyers are not borrowing too much, buyers should also check for themselves that they are not getting into too much debt, especially as interest rates are forecast to rise over the next few years.

Purchasing a property will give rise to additional costs such as solicitors fees. Buyers who don't want to live on concrete floors for the first six months will have to fork out for furniture, too.

"That's when the credit card comes out," says Mr Mackey.

Although first-time buyers' spending power will inevitably be curbed after they take out a mortgage, they may often feel that becoming a homeowner is worth not having a life for a while, he adds. "Everyone sacrifices a lot for their first home."