Welding is easy. My grandsons, with a little assistance, can get two pieces of steel to stick together. The welds look like metallic chicken poop, and crack like glass, but the boys are proud to say they can "weld."
Creating strong welds that look decent is a challenge. Preparation is the key. Start by removing all paint and rust from the surfaces to be joined, especially if you're using a MIG wire welder. Paint and rust when heated disrupt the gas shield essential for good MIG welds. If you're MIG welding and have trouble striking and holding an arc, stop and take time to grind away paint or rust. ALL the paint or rust---even a little bit of residual paint or rust can create problems. Stick-type arc welders are more tolerant of rusty or painted metal, but definitely benefit from paint- and rust-free surfaces.
Be sure to grind away paint and rust where the ground clamp for MIG welders will be attached--MIG wire welders are EXTREMELY fussy about having a good ground. Make the ground point as close to the actual weld as possible. When I weld in a combine grain tank, I use battery jumper cables to extend our MIG wire welder's ground lead so I'm "grounded" as close as possible to where I'm welding.
Then, when all the preparations are taken care of, be patient while welding. Follow all the tips your shop teacher tried to teach you in Industrial Arts Class in high school. Clamp things tightly. Tack-weld opposite ends of the pieces to keep them from "moving" as you put heat into the metal. If you're using a self-darkening helmet with variable tint, use a tint setting that protects your eyes but still enables you to monitor the pool of liquid metal at the welding point. Low-amp MIG welding may require #10 tint or less to adequately see what you're welding. Stick welding generally requires #10 tint or darker to protect eyes from feeling like they've had sand tossed into them when you go to bed after a day of welding.
Wear leather or protective gloves. It's not a macho thing---I've learned that just about the time you get things "right" and have a nice, even bead flowing, a spark will inevitably land in your palm and make you jerk or jump. If welding vertically or upside down, consider wearing a leather welding cape, sleeve or some sort of protection (a stout denim or canvas-duck jacket helps, but will get burned spots that will fray at the next washing) against sparks landing in the crook of your elbow or at the base of your neck. Sparks landing in those spots will not only make you jerk, they will make you leap to your feet and dance like a geek at the Junior/Senior Prom.
You can have the best stick or MIG welder on the market, the correct welding rod or wire for the metals you're joining, and the perfect amperage for the job, and still end up with scaggy-looking, weak welds. Simply removing paint and corrosion, then ensuring there is a good ground point, helps that welding equipment performs optimally. Using the proper tint of helmet, protective gloves, and gear helps YOU perform optimally--and without scarring.