Get a GOOD soldering iron. I think mine is a Hakko blue 40w and it is just right for soldering wires (and the tip can be replaced for when I neglect to clean and tin too many times), but don't just go by the wattage quoted on the box. Read reviews and find something that is consistent in temperature and the right temperature for what you're trying to do with it. Heating up quickly is also a nice feature. Watch YouTube videos on soldering whatever it is you're planning to solder. Make sure to tin your wires and connections.
Then, practice practice practice. Unless you do something careless like melt a connector or bridge a short, the worst that can happen is the solder comes undone and you have to go home and redo it. In order to avoid that as much as possible, tug and pull on your solders as soon as they're cooled to see if you made a strong connection. I still suck at soldering, but I'm getting better each time I try.