I started collecting components around 1992, and have also worked in the industry. Here is where I am at the moment:
- Primary Supplier : LCSC.com, which is the component sales arm of JLCPCB. Although located in China, they are highly reputable, and have datasheets behind everything they sell. You can buy high quality (ie: Panasonic) or no name, its your choice and you pay the difference. Shipping is about $8 USD (the slowest option) and is tracked and reliable. I would rather buy the cheapest option from LCSC than the most expensive from AliExpress. As a backup, I will buy from Mouser. In an emergency, I go to local suppliers.
- Catalog : Run a big Excel sheet with a link to all parts I stock, where I stock them, and their corresponding datasheet.
- Jellybeans : I keep a kit of Jellybean parts that I use in every project. Common value R's, C's, Op-Amps, FETs, BJTs, Diodes, LEDs, etc, etc. Unless I really need to vary from that, I don't. I have corresponding KiCad parts as well. You can adapt a lot of reference designs to use your jellybeans on hand if you understand the basics. This really cuts down on the stock pile.
- Scrap Parts : To keep costs down, I try and find useful scrap. Raiding the eWaste bin has been great, particularly if you find industrial electronics which tend to use high quality parts. I will occasionally raid consumer grade e-waste, but I focus on high value items like AV receivers, and stuff with linear transformers, heat sinks, etc. However, I really only use scrap parts for high value, one offs. I don't both with Jellybean scrap.