I'm new also, and thus far my path has been.
TF-51 - Practice start up, take offs, landings. With that learning DCS radio controls and how the radio frequencies work. Also it's just a cool plane to take off and land, and it's modeled really well.
SU-25T - Because free, and the in-game tutorials really do help with learning the systems. FC3 systems and definitely helped me get started.
FC3, more specifically F-15 - This is where personal preference came into play. I really enjoy A2A. Take off, landing, etc were very similar concepts to the SU-25T. I then focused on learning the FCR and target acquisition. Downloaded the hoggit training map and used that to practice acquiring targets and shooting them down.
You could use the SU-25 from FC3 or another FC3 aircraft to get your feet wet and learn the weapon systems on that craft. I actually found/find flying the F-15 very rewarding despite the lack of clickable cockpit.