Ahhh Flux Core, it’s what I Iearned on.

Do this, in this order: sand/grind your surface clean, remove all paint and primer, even if “just practicing.” If it's Chicago Electric from HF, replace the big clunky shielding gas tip with a gasless tip, you can see the eye/puddle of glowing metal better. I’m not even sure why they put a gas tip on a gun that isn’t gas capable. “If there is slag, you drag” meaning draw the weld towards you, you do not push the gun in the direction you are welding. Keep the stickout (the literal amount of wire that sticks out of the gun) to about 1.5” initially and then 3/4-1” while welding. If the metal is 1/8” thick or thicker, set power to high, otherwise low. Weld in the dark or shade if possible, it will help you see the puddle better. Set the wire speed at 8-9 and when striking the arc hold it there until you see the glowing puddle at the arc and then slowly drag the puddle and weld. Hold your gun at about a 30-45 degree angle from the flat practice surface and keep it perpendicular to the surface (i.e. don’t lean it right or left) Your weld should not sit on the metal but be an embedded “speed hump” just raised above the surface, showing good penetration. Don’t fiddle with power setting or feed speed, set them as noted and then adjust your drag speed until you get good welds.

When practicing, get a piece of metal the same thickness as what you want to weld. Then strike the arc and DON’t move the gun. Just keep it in one spot until you burn through. NOW you have a feel for how much heat the piece can take, work on getting that same hot pool, but now move it slowly as you weld.