Look at your current bulbs
Check your existing bulbs to find out the fitting you'll need from the new LED bulbs.
Use this opportunity to check you're using the right bulb power in your lamps (some have a max wattage).
It can be helpful to have your existing bulbs to hand when shopping for LED alternatives, a lot of shops and online stores have comparison tables to help.
This article has some great advice on switching to LED bulbs:
Pick your power:
LED bulbs use much less energy than traditional bulbs and as a result have a much lower Watts number than you'll be used to.
As a rough guide use the 10% rule: if you're replacing an old 100W bulb go for a 10W LED, 60W bulb = 6W LED and so on.
Some retailers have comparison tables and information to help you find the right alternative.
Pick your colour:
Traditional bulbs give off a warm glow rather than a harsh blue light.
Luckily LED bulbs have a colour rating that's measured in Kelvin to indicate the colour. As an example 1500 Kelvin is equivalent to candlelight, 12000 Kelvin would be a bright blue sky.
The lower the Kelvin number, the warmer the light colour will look.
Why is this important?
According to the energy saving trust: "Lighting accounts for 15 per cent of a typical household's electricity bill" - making the switch to LED bulbs can help cut this figure dramatically, helping save you money, and helping save the planet in the process!
Any reduction you can make to your personal energy usage will help reduce demand on the national grid, and in-turn, helps reduce the need for fossil fuels to meet demand.