During a CEUS exam the devil is always in the technical details, here I give a few tips also pertinent for this exam:

• The probe position for the CEUS should be determined beforehand - during the exam itself there is absolutely no time to figure this out or make corrections. Also a renal CEUS without arterial phase is not diagnostic. Always tailor this to the body habitus, cooperation, and respiratory capacity of the patient - in a frail, elderly patient a good freely breathing approach can get you further than a failed breath hold technique.
• Lower extremity peripheral venous access can be used if there is no other option but the dose must be increased to counter microbubble pooling in the lower extremity veins. 
• Always conduct a B-mode color/power Doppler (and if available MV-flow) survey, and always document the T0 image.
• In the arterial phase focus on one thing above all: keeping your lesion in the FOV while recording a cine loop. At least for the first few dozens (hundreds?) of exams do not focus on the enhancement pattern - you can rewind the cine loop later as many times as you want, but if the lesion slips away in a critical moment and there is no recording the exam will not be diagnostic. 
• No matter how confident are you after the arterial phase, always sporadically control the lesion until the late phase. 
• Finally, also during a renal CEUS it is prudent to conduct a quick survey of the liver in the late phase, in case any washed out lesions show up.