One very usefull acessory for any electronic starter would be a proto-board, that just for you information can be found in the link below
https://www.globalspecialties.com/powered.html
This device can be used as the first step on mounting electronic circuits, especially prototypes, before you get the final configuration that could be mounted in a printed circuit board.
The link I sent show a "powered" board, that meas it already holds a power suppy incorporated that you can use to supply your circuits.
The board is very simple to use and what it does is to interconnect the components as you place then in the board. The way the companents are connected to each other will off course depends on the electronic circuit and the board alread interconnects some "holes" to each other. Some other connections will have to be done by placing small peaces of wire to the points where the connection are required.
You probably can find extra information about how to use this device in the web before even purchasing one, or in the manual that for sure will come with it.
Man, you're right, you can find many usefull components from old junk equipment and it will work just fine. I would suggest also you buy a "DESOLDERING PUMP " that will help you to remove the components from the printed boards of the junk without demaging it.
There are many, zillions of lectronic circuits that you could start with but I would suggest you to start thinking about something you really need for you, something you are missing and then, depending on how complicated it is, you could try to build it. It is much better to build something that you can use later.
Have fun.
Nilo