Because of the wide range of nature, complexity and length of matters undertaken as well as various other factors, in order to remain flexible and provide the most cost-effective solutions to clients, fees for each case/ project are agreed individually.
In terms of fee structures, charge may be based on an agreed hourly rate, which is set by reference to the nature/ complexity of the case and my level of seniority. In some situations (though not all), it may be possible to agree a fixed fee for the entire or certain aspects/ parts of the work. Such model is typically more suitable for drafting and advisory and other paper-based work. It may also be possible to adopt a hybrid approach (i.e. a combination of fixed fee(s) and hourly rates). These are the most commonly used pricing models adopted by my legal practice and many other lawyers I work with.
Commonly used pricing models specifically for appearance at hearings are brief fees and (where applicable) refreshers.
In some instances it may be possible to provide a budget estimate for a particular matter or certain stages thereof. Please note that, whilst every effort will be made to adhere to such an estimate (where it has been provided and agreed beforehand), it is typically not "cut in stone" and some reasonable deviations may occur. 
In any event, the fee structure agreed for any individual matter will reflect what is most appropriate and cost-efficient for that case.