Get an experienced 3d pilot to balance your plane and set the cg in all 3 axis. A poorly balanced plane is a handful for anyone and will seriously limit your progress. If you can't find anyone, adjust the cg yourself until the plane will fly level, hands off both upright and inverted. Inverted hands-off may be impossible but try to adjust the cg so it is hands off level upright and as little elevator required when inverted. An experienced 3d pilot can also tell you if your plane is too light or too heavy. That makes 3d harder but not impossible.

Then practice slow speed inverted flight until you can fly perfectly level circles and figure eights in a small area effortlessly. Slow speed inverted flight MUST be second nature. I say this because anytime you screw up a 3d maneuver there is a good chance your going to be inverted with inadequate height and speed to roll upright. You have to be able to recover while inverted or you are going to crash and break your plane.

After that its entirely up to you. My order of progress was like this: inverted flight, elevators, upright harriers, blenders and flat spins, inverted harriers (delayed because my vertical cg was wrong and made this too hard until I corrected the cg), high alpha knife edge. I'm still working on hovering but getting better.

Try them all: you and your plane will make some of these easier than others so you may progress in a different order.

Good luck!
Clark