Charity shops,we have got some amazing furniture for our house from a charity shop,all solid wood,older furniture in excellent condition.We have a table,a larg bookcase,a unit and a television unit,the television unit you can store the television inside.The furniture all looks amazing and came to well under £100 for all of it.
All the charity shops where we live have curtains in them,most have furniture and all have vases and ornaments,we've also bought those from charity shops as well.
Jumble sales and carboots usually have smaller items for the home as well.
Freecycle,preeloved,freeads all usually have household items on them and lots of them are very often free as well.
With the paint,quite a few times I've bought the diy stores own brand white elmusion and then added a tester pot or two and mixed up my own paint.I buy the color I want but in a darker shade and then mix well,bamboo canes are good for mixing paint,you can either mix in the pot the emulsion comes in or if you want more than one color places like b and q sell buckets for 99p.I always make sure I keep a few empty jam jars filled with the paints I've made(5DC in the house)incase any areas need touching up in the future.
Cheap frames(99p shops,£ shops all sale really nice one's)filled with favorite pictures or posters,samples of wallpaper or a sketch or painting.
Large mirrors and soft furnisshings can be picked up really cheaply from charity shops and shops like dunelm mills,the range,b and m,homebargains,matalan,supermarkets.