You can have a lot of satisfaction from doing something correct. In order of importance is to remove oxide from the two parts to be soldered, wires are best to discuss first. Copper should solder instantly if its clean, the iron is hot and there is flux melting on the surface. You can pull a resistor out of stock and while it looks ready there is a vast difference in trying to solder a resistor's leads. Use an eraser, even a white ink eraser that is abrasive will work fine. Try for three wraps around each of the two leads you are putting together. In other words the mechanical connection is there to take the stress off the soldered connection. Big clue: if the solder balls up on the tip of the iron or the wires, stop and clean the solder tip with sandpaper or steel wool. Clean the bench, you don't want steel fibers getting into you project.
After a clean tip and cleaned parts the next impediment to soldering is enough heat. We are talking electronic parts soldering and for the record only rosin core solder and rosin flux is used to tin the leads, never acid core, thats for sheet metal workers. Lets see, a 5 or 10 watt iron will handle 24 to 40 gage wire, two ends to be soldered together. For larger wires like 18 towards 24 the iron works best at 15 to 30 watts, more toward 30 if you have more than two 18 gage wires to solder.
Next point, you have twisted the clean wires together, now to solder put a small amount of flux on the parts or if using flux core solder touch the solder to the wires to be joined about one second after you put the iron on it. Watch and in one to two seconds the solder should have flowed. Take the solder away and in the next second remove the iron. Look at the joint, it should be smooth, not rough or looking irregular.
You must experience a few soldering and unsoldering episodes, all the while watching what you are doing. Remember, if you can't make a good solder connection in the total of 5 seconds figure out if you need clean parts or more heat. In soldering transistors and pins on integrated circuits, each pin should take about two seconds. After doing a few pins, let it cool off for 30 seconeds.
Soldering is definitely a skill learined by doing. Reading the above paragraphs is the basics that must be applied. Can you imagine the skill of NASA assembly people, all there work is closely inspected, exrayed and some of them have done many, many thousands of connectons without error. Yes I know wave soldering nd other techniques have replace a lot of hand solderig but we don't have that machine at home, good luck.