Ask Lemmy

For guitar and bass:

• The mostly ortholinear grid relationship between frets and strings mean that you can think a lot about "shapes", or positions of notes relative to other notes. Unless open strings are involved, sliding any shape up and down the next gives you the same quality of chord or scale just shifted up and down in pitch/key. (Not all instruments have such an intuitive layout!)
• You don't need to memorize the note names (C, C#, D, Eb, etc.) of every fret on the fretboard! It's essential to learn the names of the open strings first, so that you can tune your guitar using a tuner. But did you know that the notes at the 12th fret (often marked with double dot inlays) are the exact same notes 1 octave higher? This means that everything above the 12th fret is an exact copy of everything on the lower half of the fretboard (cutting the task of memorization in HALF)! Similarly, because the lowest and highest string are both tuned to "E" in standard tuning, they have the same notes all the way up and down the neck (that's another 7.5% of the task eliminated). Finally, I recommend starting to memorize the note names strategically, starting with only the inlay/dot frets (3, 5, 7, and 9) on the 2 fattest/lowest strings (E and A string). Once you've memorized these key "landmarks" on the lowest/fattest strings, you can use logic to deduce the other notes pretty quickly! (What's the note between A and B? Bb! Between C and D? C#)
• Finally, learning 2 note intervals will eventually be your best friend. Not only can you use octaves to make deducing note names easier while memorizing the fretboard, but you can also play octaves to enhance all kinds of music from punk to jazz. A perfect 5 interval is the heart of the "power chord". And knowing intervals will help you do everything from reading sheet music to writing interesting guitar parts in all genres.
• The huge number of popular rock music that you hear can be played with 2 or 3 note "power chords" alone. This is important because it means that you can become proficient enough to play rhythm guitar parts with a band in a matter of weeks of solid practice! All you have to do is memorize the note landmarks on the lower strings, be able to build a power chord on the appropriate note, and strum it in time with the music! Whether it's guitar or bass, you don't need to be an expert to start playing or writing songs.
• When you eventually learn your first scale, try to learn it in 2 positions on the neck. For example, if you learn E-minor pentatonic, learn it starting from the 6th string at the 0 fret (which is the same as the 12th fret, remember!) AND learn it starting from the 5th string at the 7th fret. This may seem harder at first, but over time you will learn how to connect these scale shapes with intermediate shapes, and you'll unlock the entire fretboard for soloing!
• On a right-handed guitar, your right hand can be mostly thought of as a rhythm instrument, just whacking away at strings like a drummer whacks at their drums. Whether you hit all the strings, some of them, or just 1 string at a time, the rhythmic aspect is what matters most. It takes practice to become fluent here, but looseness and fluidity is key. Eventually you can incorporate other techniques to change the timbre of the rhythms being played, but remember to keep the rhythm going in constant movement. (On a left-handed guitar or bass, this would apply to your left hand.)