PRACTICE PRACTICE PRACTICE.
RCS needs to be balanced from the Center of Mass. With large craft, I have a set on top (stock 4point RCS quads) and a set below on the major ZY axis (0,90,180,270). Small craft I just use one set centered on the center of mass. I usually, attach the RCS last. Set your gizmos where you like them to be without offkiltering the vehicle. Found out I did an experiment putting those quads at a 45-degree difference (45,135,225,315) that 2 sets of quads fired for a maneuver instead of one. Hard to lift off from a planetary body in a vacuum with turn a tight to make orbit.
Must be in exact orbit with the same apoapsis, periapsis, and inclination...about 2km with <10 m/s is a good target distance and speed...Good luck with that.... use small RCS burns, shut off the mains and just slowly approach the target. BE PATIENT! you'll get there. Make sure your docking clamps are crossfed. At 500mtrs slow to 3-1 m/s. Overshoot sucks and takes another 10 minutes to reset yourself. DONT WARP!
I use the LOCKED view to upright my vessel and the camera always has a view ahead even turning. Keep an eye on the navball with the prograde bug centered on the target bug.
Target is always tumbling slowly...just have to get ahead of your planning at the very end to intercept and soft dock. Took me a while but well worth it. All in good fun.