Hmm, you sound a bit like me 9 months ago. I had never welded anything at that point and was trying to use an arc welder I bought from a car boot for £20. Best thing I ever invested in was an auto darkening helmet, it helped me see where to start my weld, made it much easier to strike it and see / control the weld pool. Next thing make sure your machine is set up properly. I bought a load of steel off ebay to practice on. I also got some steel washers and practiced filling in the hole with weld, it teaches you to control the current, get it wrong and you dont weld it or you burn through it. I went through a huge box of old angle iron before I went anywhere near the chassis. I used an arc welder, it's a 200 amp inverter, most people use mig. Those people are considered normal. I don't talk to them
Arc does give very good penetration, the only setting you have to worry about is current, no messing about with wire feed and gas. It does produce slag, but do it right and the slag virtually falls off.
I am not trying to convert you to arc, I am trying to get you to look at why it is going wrong and put it right. Throughout the building process you will find loads of jobs that seem hard or impossible to start with. Don't give up. Stick two fingers up to the problem, find a different way or ask for help.
I'm starting to sound like I am lecturing now so I will go away and flush my head down the toilet.
Get yerself an auto helmet, some steel, some patience and take your time.
Enjoy your build.
Enoch