Most people getting into RC construction have some experience with RC models in the past, like putting together e.g 1:10 car kits, knowledge about batteries, electric motors, ESC, radios and servos. Seams you have much of that sorted out already. The new thing is dealing with hydraulics, that one just need to get into step by step as one goes along. The hydraulics of RC construction machines is relative simple and basic compared to the 1:1 machines, but complicated enough for someone who don't have special training within the field naturally. The main issue is generally trying keeping hoses and fittings tight and leakage free, checking one have enough oil in the system. It's possible to get most of the basic know-how one need at forums like this, where hydraulics in general and specific models like the 4200XL are discussed.
Can start off with one first advice; one possible want to avoid working at an hydraulic RC construction machine at the table in the living room or kitchen, but be in the garage, basement or somewhere where potential hydraulic oil spill can't do too much damage..
