You have probably heard of Tesco? The big UK based supermarket owner with 5,000 shops in 13 countries? It is not really common knowledge, but I own this business. Unfortunately, when I went to buy the Tesco business, I did not have the £25 billion necessary to buy the whole lot, but I could afford a few thousand shares to take a part ownership.

As an owner, therefore, I was delighted this week to visit one of my shops in Ireland and see that it was looking smart and fairly busy. The “Celtic Tiger”, a term that once described Ireland, has lost its teeth and claws and is looking a bit mangy – unemployment is running at 15% and incomes are down for many of those who have work. The bling years are gone as lots of people struggle to make ends meet. Nevertheless, despite the recession, there are certainly customers buying stuff at Tesco.

They have a lot to choose from – Tesco sells just about everything: groceries, electrical goods, clothes, petrol, pharmacy and mortgages to name but a few. This has squeezed some of the other operators here in Ireland and these smaller locally owned chains of more traditional supermarkets are nearly reduced to corner dairies by comparison.

Tesco must also be squeezing the average family – the offer of wares from Tesco is so attractive that it is hard indeed to get out of the place without blowing the budget. However, there is another option for the Irish – there are two big, ubiquitous chains of discounters: Lidl and Aldi. These are owned by two German brothers who are in fierce competition with each other. Lidl and Aldi are both very, very cheap but their offerings make The Warehouse and Pak n Save look like Harrods – they are cheap, but very basic.

So, with money tight, the Irish tend to shop in Lidl or Aldi for basics, and then go to Tesco to top up with other stuff. Although I own shares in Tesco, I think that this part of the shop is a mistake – anyone on any sort of tight budget should stay well clear of Tesco.

Quite simply, the Tesco offering is just too tempting. In fact, there are studies that have shown as much as 40% of supermarket purchases are unplanned , never intended. Everything that makes a good investment for me, makes a bad place to shop for people who are trying to save money.

Tesco is brilliant at getting customers to buy stuff that they never meant to, but some New Zealand supermarkets are reasonably good at it as well. Although average New Zealand shoppers may not spend 40% of their money on impulse purchases, it will be quite a high figure. My guess is that impulse purchases are the name of the game for supermarket owners.

There are, however, a few things you can do to beat the supermarket at its own game and to keep spending in line: First, shop with a list. It is the unintended purchases that blow the budget. Those impulse purchases are exactly what the supermarket with all its design and layout is after. Only by shopping to a list and being staunch can you withstand the marketing push of product.

Second, try to shop as infrequently as possible – preferably only once a week. Each time you make a supermarket visit you are hit by messages asking you to buy things that you do not need (or at least, did not intend). One big shop is a lot better than a daily visit.

Third, convenience costs. That “quick” stop at the supermarket on the way home from work to pick up dinner probably costs a great deal more than a more considered and planned shop. This is both in terms of convenience foods costing more but also these quick visits become a habit – you are back to daily supermarket visits.

Fourth, stay away from the supermarkets that are high on display and, therefore, high on temptation. A good way to do this may be to shop for groceries on-line. On-line shopping attracts a delivery charge, but for a lot of people, this is small compared to spending as much as 40% more on things that you never intended. When you are overseas I would very much like to think that you would shop at Tesco – but in New Zealand, keep it basic and stay out of the temptation of slick promotion and merchandising.

Martin Hawes is an Authorised Financial Adviser and his disclosure statement is available free of charge at www.martinhawes.com. This article is of a general nature and is no substitute for personalised financial advice.