I’m year (3) into Car Audio. If you need to connect some wires but don’t want to solder (suck at it), heatshrink connectors, or use the other things available. Try these. Lockitt Posi-Tap 6pc pack #605/6 16-18 awg Blue
The reason to use these if you want somewhat temporary connections (but I’ve had some in there 19 years) where if you upgrade something later (stereo, backup camera), then you can disconnect and reuse these. I love them. They are more expensive than the $10-20 case of wire connectors but I use each of these. Once I’m done with something or change something, I pull them out and reuse them. They’re the best. Now they have different sizes but these blue ones work on the smallest wires so far or bigger ones. To me, this size is ideal but you can try other ones. Now this is the lazy option other than getting out the heat gun and wire connectors with heat shrink but they’re easier in my opinion. I really do both methods. If I think something is forever, I then use a heat gun/heatshrink.