First you have to make sure that you don’t pick a soldering iron/gun that is too hot for your project. A 25 or 30 Watt soldering iron will work for most small electronic work. It’s like using a glue gun. You want the tip hotter so that it works faster but it will loose heat when you are using it so you need to have patience because it has to keep regaining heat as you go along. I would try a few different kinds of tips to see which shape you are comfortable with. They are really a personal preference. It’s probably better to have a soldering iron that plugs in for continuous and consistent heat but there are a few portable options available and they may cool off faster but they may not make a very high quality connection. The reason soldering irons are hotter than the solders melting point is that they want it to transfer heat to the joint faster. So you do not want a soldering iron that is too hot or it will wreck your components. You should also figure out if you want an expensive or cheap soldering gun. The cheap guns have a shorter life and they heat up your hands when you use it too long, while the expensive guns last longer and don’t heat up your hands while you hold it and you can use a wide variety of tips. I would say you could probably get away with a cheap one while you learn and see if you will need a soldering iron long term or not.