My book about traits of effective leadership is a bloody good read. One of the other traits of effective leadership is first things first. It should be gospel too when planning a room or house refurbishment.
I've picked up the pieces so many times after a builder has been in, radiators in the wrong place (leaving no space for furniture) , sockets in the wrong place or not enough of them or clients buying furniture without checking it fits into the space first. Its has got to be the most expensive mistake not taking the time to do things in the right order.
So don't start any work without doing "first things first".
Even if you don't have the budget to do everything you want at once do the messy or architectural things first. Its about prioritising your spend and to a certain extent being brave about what you do spend. I have learnt my lesson the hard way. All my life I have renovated houses and over the last decade as a developer looking to maximise profit. Sometimes you have to admit that sometimes spending less can be a false economy. Once of my first developments was an amazing Victorian house, the surveyor tried to convince me that spending an extra £10k on knocking the kitchen through to the diner would create an amazing space. I didn't do it as I wanted to stick to my budget. The first viewing took place when the house was finished for sale and turned it down as they wanted an open plan living dining space! I missed my chance the market slowed down and I had to drop the price by 25k to sell it. Wish I had upped my budget.
Any way start at the beginning -
Start with space - if walls or doors needs to come down or move do it, it may add value to the property which you'll recoup when you sell.
Furniture, existing and potentially new furniture, draw a room to scale on paper and do the same for your your furniture and move it around on the plan until you get a logical floor plan. Its much easier than lugging furniture around too!
Do the same for Lighting and electrical points - where will the lights go, where will the sockets need to be, will I need more or to move them to work with my floor plan. Even with kitchens before you get seduced by the glossy brochures start with a b&w plan which sets out ergonomically what could work.
Same with colours, put all your fabrics, wall colours and floor covering samples on a board, don't buy anything until you are sure that you can get materials that will go together. I have seen projects where a colour or tile has been chosen and implemented only for the client to take years to find a flooring or fabric to go with it.
Even think about whether radiators can be moved to make them less visible or make room for more furniture. We've just had a client agree to remove their existing hall radiator which is about 1.5m long and replace it with a vertical one which is only 0.5m wide. Which now means we can fit in a neat storage unit in to the space. The whole space is going to look so much better.
Doing the space planning stuff move may cost more money up front (moving rads, adding sockets) but needn't be a bank breaker, it will give you better results and anything thing else will be just be a compromise.