- don't cheap out on breadboards unless you plan to manually test every single connection regularily before prototyping
- with some breadboards the (red/blue) power rails are not connected all the way through, but only for half of the board, in doubt always measure. If this is the case with your board, just bridge the rails once and leave them bridged forever.
- if you prototype projects more often get yourself sortiments (e.g. a resistors, film capacitors, ceramic capacitors, electrolytic capacitors). Yes, these sortiments are expensive, but my first private resistor sortiment lasted me for a decade and if you calculate a decade worth of "fuck that part is missing" it is a no-brainer. I literally never regreted getting those.
- if you constantly find yourself using certain connectors build a (heavy) breakout-box for them. Something that doesn't fly off the table easily. Having your breadboard fly of the table because your guitar is connected to it is bullshit.
- there are limits to breadboarding. If you go high voltage, high current and/or high frequency or anything extra sensitive avoid it
- learn how to translate between schematics and breadboards. Nowadays there are many breadboard-illustrations that show you exactly how to connect things. That is neat, but ot is hard to reason about circuits that way, and this will be needed once you deciate from what you find. Most interesting circuits will come as schematics anyways, so learning it is worth it
- if you breadboard complex schematics, print out the schematic and tick off (with a pen) every connection between every pin of every component you make. It is very easy to miss something even for professionals. In the end a circuit is basically just nodes (a single pin of a component) and edges (the connections between them). If you get the topology right, the circuit should work. Exceptions: the schematic is wrong (not uncommon, there is a lot of crap on the internet), the parts are wrong (there is many nuances to each part, beyond their basic value) or the circuit is of a kind that is not suited for breadboarding (see above).
- Sometimes people online claim that X works, but it only works because the part they had lying around had a very specific characteristic that they conceniently failed to mention. It is okay to just give up and move on at some point
- Try to simulate schematics before you breadboard them. Change component values to get a basic intuition for the circuit. I like this one: https://www.falstad.com/circuit/circuitjs.html (it has some limitations, e.g. inverter based relaxation oscillators won't oscillate, but for the most stuff this is fine)
- don't forget to add bypass caps. Just get a sack of ceramic 100nF capacitors and sprinkle them between plus and ground on the power rails next to wherever tou put active components (chips, etc)