alright so i hope this helps you as opposed to just making you more confused. fillins tend to be more about flow cause well you sure as hell dont wanna have to be doing alll this complex shit save that for the pieces or until you know more about what you're doing.
every letter i did goes in the direction of the left with the exception of the top of the S. this sets it up nicely to for you to do the next letter. you can see where i crossed the line of the other letters and if you follow the direction of the line it goes down to the bottom right-ish of the letters.
you almost get like momentum(?) doing things like this(?) its just so much easier and more efficent than some stop and go. also it just looks better once you get a hang of it. hope this helps
oh and by no means do you have to do the letters like this just the way you draw them should be similar to each other letter in the way it looks/it's properties.