There are too many options to get started with electronics!
From the soldering iron to get, software to use, and PCB fab houses to work with, there are too many to choose from. And this would lead to analysis paralysis. I am here to point you in the right direction on what you should start with in your journey to designing, assembling, and testing your own electronics.
I can tell you right now: a soldering iron is an essential piece of equipment you'll buy. As such, a cheap $10 one from eBay can often do more harm than good. I made the mistake of buying one of these as my first soldering iron — I burned a hole in my kitchen floor when the tip came out. I've also heard stories of some Chinese models starting fires. Don't skimp out here. I recommend getting cartridge-styled soldering irons instead of the ones with replaceable tips. These styles of soldering irons offer better performance by far as compared to the replaceable tipped versions.
For most scenarios, lead-free solder is the preferable choice. You get almost all the benefits of leaded solder without lead poisoning. 0.5mm or 1.0mm solder is usually fine
This paste is used to help produce high-quality soldering joints when you solder. It cleans the surface and temporarily prevents oxidation from occurring at the joint.
Multimeters are an essential tool for every lab. Their plethora of functions allows you to debug and test any circuit imaginable. Getting one with a continuity testing feature is especially important!
Make a mistake? A solder sucker can probably fix it! Simply heat the solder, depress the plunger on this tool, push the button, and it will suck up the molten tin.
You can pick up a variety pack of wires that are 22 - 28AWG on Amazon for an affordable price. Get both solid and stranded. Solid for breadboard work and where you need the wire to be stiff. Stranded
Breadboards are an excellent resource for prototyping a circuit. Unless I'm sure that something will work, I generally try and breadboard it before soldering. Breadboards are great because they allow you to adjust your circuit easily. Perfboards and protoboards are a little more permanent, as they require soldering. A protoboard is like a breadboard in that it has connected rows. Perfboards are just a matrix of holes you can solder to without connections between holes. Both have advantages, but more often than not, I'll end up using a protoboard over a perfboard. It takes up more space, but less wiring and soldering are involved.
Any 30V 3A power supply with variable output should cover most applications to power the electronics.
A good starting point for electronics schematic capture and PCB design would be KiCAD. There is a large community around this software, it's free, and it's open source. Tutorials are readily available on the internet on how to use this. Some even hold your hand up to the point of getting your board manufactured by a PCB house.
KiCAD is the best choice for those that are starting out and hobbyists. There is other software out there that is more advanced than this. Such as Altium and OrCAD; however, these would cost $10,000's to purchase and use. Leave those to the professionals and businesses.
The three major PCB manufacturers to know are JLCPCB, PCBWay, and OSHPark. These three provide high-quality PCBs at an affordable price and fast turnaround time, depending on the design and project requirements. As a beginner or hobbyist, most of your PCB manufacturing needs would be covered by these companies. However, if you need more advanced features, such as multiple layers, unique materials, and automated assembly and testing, then I can recommend NextPCB. I had used them before and was happy with the PCB quality and service they provide.