I have found in my many years of welding to work side to side, if you will wave the weld between the pieces of metal and move slow. I find a bead of 3/8 inch is more than sufficient for a heavy weld and you can lighten up on the width you wave when your dealing with a joint that is not stressed as heavy you can just tack weld where you only weld small beads every 3 or so inches depending on how much strength is needed.
Cleaning the metal surfaces is a big deal as well I have found, be sure the metal is clean and well buffed where weld is to be placed and it makes the process much easier and there is less a mess and a much stronger weld.
Practice will make this easy and you will gain much confidence. When I started I got a bunch of scrap metal from a fabrication shop, (cheap) and welded strange odd pieces together until I got the hang of it.(17 years ago)LOL
I guess I have grown up!!!
Hope this helped!!!