Blondes look beautiful, but are notoriously hard to maintain. Roots will show through quickly, and the colours that the hair is toned with will tend to fade a little bit over time. If you are committed, then silvery blondes can work well, but do be aware that you will have to work on the colour to keep it fresh.
First of all, talk to your hairdresser about whether this is a realistic option for you. Sometimes, silvery blondes just won’t work with your natural colour, or the colour you currently have on your hair. They will be able to give you advice and you can look at colour charts together to find a suitable shade.
Use the right shampoos after your colouring appointment. It is usually important to use shampoo that is sulphate free, as this is less damaging for your colour. Protect your hair from the sun, and make sure you book in for regular colour appointments.