Welding Tips and Tricks

Beginner Mig welder here with a newbie question. I'm fabricating a bumper with a spare tire swing arm mount for my '95 4WD Suburban. I use the truck primarily for my landscape photography outings but the inside-mounted 33" spare takes up way too much room so I decided to take on a new project. I've been doing a lot of practicing with 1/8" and 1/4 " coupons with the classic T-joint, as well as vertical up and vertical down welding. I'm now at the point where the real work begins. To fabricate new bumper mounts, I'll be using 3/8" bar stock and 1/4" plate...the 3/8" bar will bolt to the frame horns and the 1/4" plate will be welded perpendicular to the 3/8" x 5" bar (the existing frame rail was built using 5-inch channel so I decided to make the new brackets the same width. These will be the critical welds since they'll be supporting the bumper and swing arm. My question is, is there a special technique when welding metals with different thicknesses, or in this case is the difference small enough where I don't need to be overly concerned? Or am I overthinking it? I'll be using 0.035 wire with 75/25 gas. Any insight would be greatly appreciated.

Can you post a pic or sketch of what you are proposing?

Yeah there is usually, while getting peno, you favour the thicker material slightly so you can burn into it and not terribly undercut the thinner material. It would help to do some practise runs and cut then to make sure you got it. Grind all areas you intend to weld clean.
Even if you do out of pos welds well i.e. verti up, overhead etc but you dont usually if you dont have to, so do as much in the downhand pos as you can.
You probably have the paint sorted but epoxy enamel is good for that sort of stuff too.

Something critical to bear in mind, when you weld that bumper up, the added heat will “pull” the entire thing in many directions making the fit problematic. You need to be very mindful of the tolerance in the mounts and intentionally create more space in the fit that you can pull out with bolts and nuts.