An insertion device for inserting a catheter into a body of a patient, comprising: a housing defining grip surfaces on either side of the housing for enabling grasping of the insertion device by the user; a hollow needle distally extending from the housing, at least a portion of the catheter pre-disposed over the needle such that the catheter is disposed substantially external to the housing, wherein the hollow needle occupies a lumen of the catheter defined by a catheter tube which extends distally from a catheter hub of the catheter, wherein the catheter hub is initially disposed adjacent an open distal end of the housing; a guidewire; a guidewire advancement assembly including a guidewire lever including a finger pad slidably disposed with the housing and movable by the user to advance the guidewire, wherein the guidewire advancement assembly is configured to selectively advance the distal end of the guidewire out a distal end of the needle; and a catheter advancement assembly configured to enable advancement of the catheter in a distal direction, the catheter advancement assembly comprising an advancement member initially residing within a cavity defined by the housing and being used in selectively advancing the catheter in a distal direction during use of the insertion device to insert the catheter into the body of the patient, wherein the insertion device is configured to be grasped by a single hand of a user during use, and wherein advancement of the guidewire and the catheter is configured to be achieved by the single hand of the user by placing the grip surfaces and the finger pad for user grasping of the device, enabling the finger pad and the guidewire advancement assembly to be used to advance the guidewire and the catheter a predetermined distance, followed by manual advancement of the advancement member by a finger of the user. a housing defining grip surfaces on either side of the housing for enabling grasping of the insertion device by the user; a hollow needle distally extending from the housing, at least a portion of the catheter pre-disposed over the needle such that the catheter is disposed substantially external to the housing, wherein the hollow needle occupies a lumen of the catheter defined by a catheter tube which extends distally from a catheter hub of the catheter, wherein the catheter hub is initially disposed adjacent an open distal end of the housing; a guidewire; a guidewire advancement assembly including a guidewire lever including a finger pad slidably disposed with the housing and movable by the user to advance the guidewire, wherein the guidewire advancement assembly is configured to selectively advance the distal end of the guidewire out a distal end of the needle; and a catheter advancement assembly configured to enable advancement of the catheter in a distal direction, the catheter advancement assembly comprising an advancement member initially residing within a cavity defined by the housing and being used in selectively advancing the catheter in a distal direction during use of the insertion device to insert the catheter into the body of the patient, wherein the insertion device is configured to be grasped by a single hand of a user during use, and wherein advancement of the guidewire and the catheter is configured to be achieved by the single hand of the user by placing the grip surfaces and the finger pad for user grasping of the device, enabling the finger pad and the guidewire advancement assembly to be used to advance the guidewire and the catheter a predetermined distance, followed by manual advancement of the advancement member by a finger of the user.