Typically the sofa will be the most cumbersome objects in your removal itinerary. If you're going to have a go at it yourself then preparation is key. If you have any kind of back problem then forget it - it isn't just the weight but the awkwardness that can end up straining or damaging muscles and joints but if you want to have a go then read on...
1. Buy some rubber 'palm' gloves. They'll cost under £5 in a trade store like Jewsons and the sticky service will grip the fabric / leather much better and transfer the weight to your shoulders rather than in your hands which will tire out first.
2. Break the sofa down into its smallest pieces. Do not be fooled if it feels light to begin with because you may have to maintain 'the lift' for several minutes and muscle fatigue can set in quicker than you think. Separate out corner units, take the bed element out of a sofa bed and have some tape handy to secure any spring loaded parts or wires. Put all cushions and covers to one side. If your sofa is still heavy - in the order of 50kg or more consider leaving it to professionals - you are likely to damage the sofa, the walls, yourself or all three!
3. Before lifting, assess your route which will typically be from the living room to outside the front door perhaps with stairs and corridors in between (and vice versa). To get a long sofa into a corridor you may need to stand a 2-3 seater 'on it's end. Before you no this consider that the full weight of the sofa will be pressing the fabric into the carpet or wooden floor so make sure the floor is clean and for white furniture again consider a professional since the item will probably need to be wrapped up and protected.
4. There are 2 most likely places a 3 seater or large 2 seater can get jammed - moving between the living room and a corridor and in a narrow stairwell. If it looks like it could be 'tight' for either - take of the sofa feet - all 4 either by spinning or using tools - this can also save damaging the walls.
5. OK so let's get moving. Having taken off all cushions and covers, stand the sofa on it's end. Is it taller than the door frame. If no then slide / push it across the floor until it is into the corridor. Do not drag the fabric if their is an indent at the base of the doorway which can damage it. If the sofa is taller than the door frame then lean it towards the door to get under the frame and then push it upright once in the corridor. If the corridor is not wide enough to angle it first then again you'll been professional advice. Repeat similar process until you are outside / inside and use a similar technique for lifts.
6. For a typical stairwell, you'll need to configure the sofa so the seats are facing 'inwards' towards the bannisters. The 'indent' of the seating area can then ride around the bannister as you go up or down - be warned this is tiring work when holding the sofa at an angle in a confined space where nobody else can really help. If it gets wedged and there's not far for it to get round give it a little wiggle but not too hard or it could be impossible to retrieve either way and you'll be blocking a fire passage if it gets stuck. Do not be surprised if the pressure marks or scuffs the wall - this may be unavoidable. Also do not be tempted to try to take through a window - this is both dangerous and can be very costly.
7. Once you are out of or into the property, collect the cushions and keep the feet and any screws in a bag for the next part of the process.