I'll try and explain what I've taught myself. First, I'd recommend going to the hobart forum and poking around. My torch is usually at about 10-20* angle from the joint if it's a butt weld, corner welds (fillets) is typically 45* (pointing the tungsten directly at the center of the joint) This is what you're mainly going to be doing on all the tubing.
The torch controls the puddle, actually your foot does. I'm betting that tig machine has a pulse feature. Find it and turn it off for a while. Pulse with your foot to learn your rythm. NEVER start the puddle with your filler. Get the metal melting and then add filler. Don't lay the filler down, feed it into the leading edge of the puddle. So the rythm would be- start the puddle, fill, add a little more arc then let off appx 1/2 pedal, fill, mash the pedal, let off 1/2 way, fill, mash the pedal, let off........... The end of the filler should never leave the gas shield. And don't leave the filler in when you give it full juice.
I typically find that I'm not using enough filler when I'm getting the concave looking bead. Sometimes it's too much heat though. It's just a learning/ practicing thing.
I like to use 1/8" 2% thoriated tungsten and 3/32 filler ER-70S6 is my prefered for mild steel when it's in the 1/8"-1/4" thickness. Make sure it's S6, it seems to flow better to me. When you sharpen your tungsten, hold it straight up and down and rotate it against your grinding wheel. The grain of the grind needs to be inline with the tungsten. In other words, don't sharpen it like a pencil sharpener. Also, the grinding wheel you use to sharpen your tungsten should ONLY be used for sharpening tungsten. The finer the point, the more precise your arc control is. This is one of the crucial things it took me a while to figure out. Typically my "cone" on the end of the tungsten is appx. 3/16" long when I'm doing 3/16" thickness. The second you dip the tungsten into the work- STOP, regrind it and get back to screwing up more :laugh3:
Use a #6 cup for most everything you can. I use a #4 in tight corners. Your tungsten sticking out of the cup will vary depending on what kind of joint you're doing and how much space you have. When I'm doing something flat, usually it is less than 1/8" out of the cup. It all depends though, once again this is a practice thing.
There's tons more, but that should get you going. Ask away when you run into problems and I'll see if I can help.