The principle to understand is that the SVC has a anterior position in the chest and the IVC has a more posterior in the abdomen.
First .: You start above the right clavicle to visualize the SVC then you angulate slowly posteriorly to see the IVC in the bicaval view.
Second.: You start from the subcostal view to visualize the IVC then you angulate slowly anteriorly to see the SVC in the bicaval view.
Third.: You start from an horizontal view of the Right ventricle 2 chambers then you make an anterior move to find the SVC and angled slowly posteriorly to see the bicaval view .