@ jrtyler18943 - you will receive countless responses of "do this....do that....good....bad....etc". Here's a recommendation.
1. First, core knowledge. Understand and internalize the effects of modulating injected heat and the rate of advance (travel speed) into a workpiece. Watch and listen to Karl Hoes (Instructor/Metallurgist, Lincoln Electric) explain the tactic.
http://www.youtube.com/watch?v=3j-ciGVAxes
2. Second, attack approach. Joint geometries can be simplified via the acronym 'BCTEL'.
Butt (groove),
Corner (inside, outside),
T (fillet),
Edge, and
Lap.
Recommend you train and become proficient on welding joints
in the following order: Lap, T, Corner, Butt, Edge. For
mild steel, source/slice 20ft (HRS) sticks or 12ft (CRS) sticks of 2in wide x 1/8in thick material into coupons measuring 2in wide x 6in length x 1/8in thick. With three individual coupons you can weld a lap joint (both sides) and then lay down a fillet weld to create a t-joint. Excellent training tactic that minimizes net material costs.
With these practice coupons use 3/32" tungsten and 1/16" ER70S-2/6 filler. Then, transition into the remaining joints vis a vis Corner, Butt, and Edge. If you
start with mild steel, then attack stainless steel, and then aluminum. For aluminum, employ 3/32" filler.
Have heard many fabricators say to start with thicker (ie. 3/16in+) material to learn the process. Totally disagree based on item #1 above and from a cost perspective.
3. Third, mission mindset. Every single weld line you run should have a "purpose". If you run into an issue or have a question at this point, simply stop. ReGroup, modify your approach, and resume activities. Focused hood time, test and learn, test and learn. That's the hustle.
Good fortune with your journey.
Purpose, then passion. Practitionership. Obsession and hard work. That's the discipline.