Avoid debt and credit cards while furnishing house. If you need flooring it's the actual extras that catch you. The adhesive, grout and Reims for tiling, the damp seal, underlay, trims and beading. These cost the same whether you but good quality or poorer quality products. If buying wooden floor look for AC 4 or 5 as these are harder wearing and will not mark easily.
A lot of charity shops now have a furniture section some of the furniture can be of an excellent quality. You could pick up sitting room suits, tables, chairs, etc for a few hundred euro. Check second had furniture shops for ex hotel beds the quality will be excellent you will often find odds and ends in both these places as well.
IKEA for all the smaller bits and pieces, from utensils, glasses, tableware, pots and pans to bath mats, curtains, toilet roll holders. But check around other stores as well.
If you are capable a but of DIY such as hanging curtain rails and toilet roll holders you may need some tools. Lidl do a excellent brand in Parkside a batter drill is a must for anything from hanging curtains rails to putting flat packs togeather.
Electric goods some things are a priority, you will need a washing machine, and hob, you will get away without an oven for a while if need be, a microwave, you could do without a dishwasher for a few years if need be. You may come across some bits and pieces on DD. If you decide to buy all your electric goods together got to a few electric shops and most will give you a discount for buying 4-5 items together it might only be 30-50 euro but money is money