Even a wire loop is so easy to overlook, but it can affect almost every part of a small piece. The loop can attach the beads, charms, and ear wires to the pendants and the jump rings. If the loop is lopsided, twisted too far over, or squashed flat, the whole thing can look sloppy regardless of how carefully you chose the beads and colours.
More often, it is about how you hold the tool. It is easy for a beginner to hold the round-nose pliers tight, since the wire can be small and difficult to grip. That can cause marks from the pliers, flatten the curve, or cause the loop to close at a weird angle. A clean loop is a result of better placement, not just a stronger squeeze. The pliers move the wire, they do not have to force the wire into position.
If you are new to this technique, try a piece of practice wire first. Cut a handful of wire lengths, and make a loop on the first. Do not worry if it is not a perfect piece for a charm. Instead, pay attention to where you placed the wire on the round-nose pliers, where you moved your wrist, and how the loop came together. If one is bigger than the next, double-check if you placed the wire at the top or bottom of the tapered part. A small difference in position is all that is needed.
You can also use your hand movement to help you. Instead of moving the pliers, move the wire on the tip of the pliers. If you move your wrist too sharply, you might get a loop on an angle that is not quite level. If you move too much with a tugging motion, you may get a loop that is narrow at the top or the neck that bends a bit. Take a moment after shaping the wire and before closing the loop. Check the loop before you close the loop, or before you open the loop to re-adjust it.
A good test to get a feel for this is to make a loop without adding anything to it. Put them on a white table or on a beading mat and look down on them. Are the loops roughly the same size and angle? Can you see that the wire comes cleanly back towards the wire stem? It might seem like a simple exercise, but looking down on them will train your eye to spot differences that you might miss when looking at them while holding them.
In wrapping a loop, you should also give it extra time, because it may be easy to make the wrapped section look messy if it is pulled with uneven tension and the wraps are not laid out evenly in one direction. Keep the first loop a reasonable size to work on, and then wrap the wire close to the loop with little pressure. Just two or three tidy wraps looks nicer than many wrapped ones that overlap and scratch each other.
Remember you are working towards something much bigger than a few practice loops. Keep working with a light hand and see if you get more even and uniform practice loops over time. You will soon notice that there is a marked improvement that is a better measure than the speed at which you work. When you are making several practice loops with fewer marks left by the tools, smoother lines, and cleaner closures, you are well on your way to making your earrings, pendants and smaller charms with a greater sense of control before you even get to the fun part.