Woah woah woah. Lets slow down and talk safety first
Are you welding on a 1900 box cover? If so STOP
Don't weld anything plated, coated and especially galvanized.
Galvanized fumes can kill you. No BS. Google phosgene and welding
here is one of the many articles you will find
https://www.finishing.com/164/33.shtml
Get a grinder and a flap disc. Yes it's for grinding down welds but it's also used for prepping your material. You should be welding on clean metal. If you have some rough mill scale to remove soak the steel in white vinegar overnight.
Wire:
.023 is great for thin stuff. Think auto body panels like 14/16g. It can't carry a shit load of amps so anything you do over 110v input you will want to step your game up to .030 wire
.030 wire IMO the best all around size. Not too small, handles upwards of 200amps (IIRC)
.035 solid wire. Great if you are welding thick plate. Too heavy to feed through a 110v welder
.030 flux wire - don't waste your money
.035 flux wire - it's flux, it works, it's smokey as fuck and it burns hotter. I don't care for flux but it has it's place. Get a tank of c25 gas (argon/c02) and your welds will look much cleaner, no slag to chip off and less smoke.
The reason people tell you not to use the wire in the box is because it's crap. It's not wound up correctly and layers overlap others so it will just pinch itself while feeding and cause headaches. Get some 10lb spools, it's cheaper than the over priced 1 or 2 pound spools
Helmet:
I can't stress this enough. Get a GOOD helmet. And no a $50 helmet isn't good. It's the difference of having a light on or off in comparison. Set your shade to a lighter number like 10 or 11 and adjust it while welding to find a setting you like. If you still can't see at all its most likely that there is a clear film on the inside clear cover of the helmet that you didn't remove. Some places tint that film green so it's easy to notice but usually the other side is clear and you don't notice it's there. But once it's removed you will notice a huge difference in clarity.
Metal:
Get a big long piece 1/8" thick from lowes,homedepot etc and cut it into 4" sections.
Onlinemetals.com
Alro Steel
Gas:
EWS in Elk Grove Village or Terrace supply in Itasca, wheeling or Villa Park. Airgas is a rip off
Links:
weldingweb.com
weldingtipsandtricks.com
welding:
you do not touch the contact tip to the work piece. The wire will touch it or appear to at least but under a microscope it really doesn't. The contact tip needs to match the diameter of the wire also. And they do wear out so every few pounds or less change the tip. The tip has a hole that is .005 oversized from the stated size to allow the wire to pass through. The contact tip transfers the current from the tip to the wire to make the circuit complete. Over time it wears out and can cause the wire to sputter or just not weld as smooth.
Polarity:
this is a big thing that new guys usually miss. Welding with gas vs flux uses a different welding polarity. You open the door and switch the leads (turn the welder OFF) when you change them
Wire tension:
Less is more. Do not overtighten the pressure on the drive roll. It will pinch the wire and then you will not have a good time welding. You want just enough tension to move the wire. Hit the button and the top drive roll SHOULD slip just a bit before pushing the wire
Do not over tighten the spool that the wire sits on. That can cause issues with feeding too. Do not let go of the mig wire unless it has tension on it through the wire feed assembly or unless you bend the end of the wire, pass it through the hole on the spool. It's tension wound so if you let go it will unwind itself and you may as well just throw the wire away at that point
Fire extinguisher. Get one
Cover up all tanks, bottles and flammable shit. I don't even own tanks of oxygen or acetylene.
Magnets:
Work great, don't weld too close to them. You will crack them but more importantly they will 'pull' on your arc
Know your limits:
I used to tell all my customers that 110v welders are good for 1/8" thickness and don't weld anything load bearing beyond 1/8". Can it be done? Yep there are tons of tips and tricks but lets just keep it at that. I had some kids come in one day trying to weld a 1/4" thick steel trailer with a 110v mig and some .023 wire. And anyone that knows me knows I do not drive behind trailers for that very reason.
Practice:
Some people push and some pull. The saying is if there is slag drag. So you pull when doing flux. For mig there are a lot of debates on if you should push or pull but do what is comfortable for you and play with manipulating the torch during your weld.
Can you weld aluminum?
Seems everyone with a mig has this question. Short answer is yes. Long answer...you need aluminum wire most likely 5356 as 4043 is generally too soft to push up a 10' gun but it can work. You use an oversized tip "generally", you need 100% argon and it takes a lot of skill. Or use 4043 wire and a spoolgun. You will not be stacking dimes or anything close to it. Maybe stacking bird shit, but yes you can do it.
I've been welding for 8 ish years now. Bought a mig and taught myself and then onto tig. I sell welders, plasma cutters. I used to work for another company doing the same and giving tig lessons and doing repairs and things like that. Hit me up if you have any questions, not sure what to buy or whatever, happy to help.
Attached two pics of some of my tig work and if you want to see more check out my IG
https://www.instagram.com/gamblegarage/