Additional useful tools

Magnifier

This could make your soldering experience a little more enjoyable, especially when doing some more complicated projects.

Multimeter

A multimeter can be used for many things: testing tricky connections, measuring battery voltage, testing resistors & capacitors, measuring the current consumption, and more.
It’s a useful tool when you’re trying to figure out what went wrong with any electronics kit.

Solder wick

You can use solder wick along with the desoldering vacuum tool to clean up any soldering mistakes. Just put it on the wrongly soldered joint and press on it with a hot soldering iron, then it will soak up the excess solder like a sponge! 
Useful for fixing solder joints when they cannot be easily reached with a solder sucker.