Take some time to consider the role of the kitchen in your home and who would be the ones using it before starting to define the requirements for your new kitchen. How much do you actually cook in the kitchen, should there be some space to eat and when you invite your friends over, should they be able to fit into the kitchen as well?
Take a note of everything you might wish to do in the kitchen and the appliances to grant these wishes. Obligatory fridge and hob can be assisted by dishwashers and coffee makers, steam- and microwave ovens plus a whole lot of other devices to make your life more comfortable. A lot of these devices can be integrated into the furniture.
Now it would be a good time validate your wishlist against the reality and take accurate measurements of your kitchen. Note the exact location of doors and windows, also the connection points with water mains, waste, gas and ventilation are important as moving them usually proves to be quite expensive if not impossible.
Bear in mind that the key to comfy kitchen is ample of space for food preparation and storage. Plan at least 1 meter of worktop space for food prep. The more the better. The same goes for cupboards and cabinets. Leave at least 1,2 meters of space in front of cupboards, drawers and appliances, that is if you want to be able to actually open the drawers and cupboard doors.
Take your time and toy around with different kitchen setups. The L-shaped kitchen is not the only possible solution out there and the island may be cool but seldom there is enough room for it.
Try to fit the sink, the fridge and the hob not too far from each other when planning, otherwise a simple case of cooking a meal will lap up serious mileage and become a real physical challenge.
Do not forget about electricity. A lot is never too much when it comes to wall sockets and there never seems to be a worktop that is overlit. Aim for more. Any wiring done after the kitchen has been installed usually proves to be complicated.
Thoroughly go through all your choices one more time after you have all that planning done. You should now have clear enough vision of your future kitchen to start shopping for the actual furniture and appliances.
And one last word of advice: always go for the best applinces you can afford. Marble worktop and oak panelling can never replace a truly efficient dishwasher or a state of the art coffee maker.