I think its helpful to understand the basic principles of soldering. There are obviously tons of youtube videos out there.

The underlying mechanics of soldering are that you are effectively making a metal to metal connection, which serves as both electrical conduction, and mechanical strength. The key to making good solder joints in the mechanical sense, is to ensure that the solder reaches the full melting point, so that it flows as a liquid. Once it flows as a liquid, it will wick onto/into the metal you are trying to fasten, the components and circuit board.

There is a second component to solder, flux, which essentially optimizes this flow. As you heat the solder, the flux activates, as well as boils off. So this is why its somewhat time sensitive. It is during this activation period that the solder is optimally positioned to make good joints. If you just leave the iron right on the solder for too long, the flux burns off, and the metal starts clumping again, becoming less like a liquid and more like a solid. In this state, its kind of a losing battle to continue to attempt to form a good solder joint. The caveat to flux is that you must clean it off when you are done, as it is corrosive. There are no-clean fluxes out there too, meaning that they don't need cleaning.

Thus, I've found the key to being able to solder well is to pay attention to the flux, and the viscosity of the solder. You can get flux by itself, to add as needed. You can buy it in a marker, or a bottle. This is very helpful with small pitched parts, because it allows the solder to wick very efficiently, as opposed to forming unwanted solder bridges.

When your solder joint cools, you want it to be a nice hyperbolic transition from the horizontal plane of the circuitboard, to the vertical surface of your part lead. In other words, you want it to be concave, as opposed to convex. Another key metric to look for is the shininess of the cooled joint. If its dull, its because some part of the process didn't happen correctly. Add some flux, and hit it again.

In terms of actual technique with the soldering iron, the key science to remember is heat transfer. You are taking one hot piece of metal (the iron), and mating some surface area with another piece of metal, the place where your component meets the circuit board, with the goal of heating that second piece of metal to the point where it will melt the solder. Thus, positioning the tip to have maximum surface contact with your joint is beneficial. Dont be afraid to put a decent amount of pressure as you are applying the tip as well. This will increase that surface area, and the heat transfer.

Finally, this is going to make smoke, and get chemicals on your hands. If you just have a fan blowing at your work area, you are defeating all of your heat transfer work. I've found using a small desk fan, and just having it far enough away to draw the smoke away is a good compromise. Point the fan away from the work, not towards. Also, wash your hands after you solder. You don't want to put that stuff in your body.

Buying some through-hole protoboard with individual solder pads, and some resistors is a good way to practice. Dont worry about the circuit your building, just try to get the hang of making good solder joints.