More of the ideas which could be implemented depend on the location and site where the garden is to be made. It would start with an elaborative measurement of the area so that it could be observed of what planting could be done. The soil should be examined to figure out what shrubs will be suitable for it to sustain and what will not be. A few other things such as the water providing system and the light arrangements should be considered as well.
There could be a need of certain changes in the garden which you want to design. The soil might not work out for some of the plants, the drainage system might not be as efficient, and there might be some issues with the length and the height of the plants also. These problems can happen once or twice a year. Make a note of all these things and make sure the garden designer you hire knows all these points as well.
A garden designer should help you with all the information of plants and flowers. This is the field he or she should be an expert because it is going to save you plenty of time and hardship. Your garden designer should tell you what flowers, pebbles or water themes would work out best with the location and lighting scheme.
You also need to make sure that the person you hire for the garden work has enough idea about places where gardening elements and tools are available at cheap or reasonable rates as it would save you cost sharing in buying any expensive material.