harpen your tungsten well, leave about a 1/4'' of it sticking past the cup so you still have lots of gas coverage.
Keep a tight arc, do small circles and add your filler as you move the arc to the back of the puddle, away from the leading edge where you are adding.
Use the smallest tungsten you can for the amperage you are running, if it is 1/8'' material use a 1/16'' or 3/32'' electrode, for 1/16'' material and light gauage sheet go even smaller like a 1/16'' tungsten or .040''. The smaller the tungsten the better your arc characteristics will be, just don't go over amperage or you might burn up your tungsten.
Hope this helps.
Do some practice just fusing metal in a lap joint or corner joint without adding filler and get good at manipulating the arc and practice making your circles, visualizing when you would add in the filler.
Cheap the torch just off 90 degrees but still pretty straight, if you bend if on too much of a forward facing angle the heat of the arc cone will be projected in that direction which will potentially melt your filler before you dip it in the weld puddle.
Clean your material very well, the more time you spend prepping material the better it will weld.
Also purge the weld area with shielding gas before you start welding, give it a solid 3-5 second burst of gas before striking an arc.
Sometimes more he is better than not enough, you want to beable to wash your added filler metal in as fast and as fluidily as possible, if you have to stop to melt a glod into the weld puddle you are wasting time and it will show in your finished weld as a irregularity in the weld bead.
If your welding a fillet rest the cup on 1 side of the fillet for better stability and just ratchet it along the joint to get your manipulation.
I like to preheat the start of my bead for a few seconds and then get a good weld puddle going before i start moving forward, so i can just feed the filler rod in as i move and don't need to dip it.
If you maintain a good weld puddle it will be your arc manipulation that determines how the bead looks and not so much when your adding filler, but you want everything to be as constant as you can get it for a perfect looking bead.
I only work with a high frequency pulsed machine so i can control my initial amperage, post flow and pulses per seconds alogn with a million other options but just having high frequency or atleast an amperage control will help you alot, since you can add more heat or less heat when you need to.