Learn. Before a person can write a sentence, they must learn how to write, and must learn words. In comparison, a person cannot write music without learning the fundamentals. For the guitar, an aspiring player needs to learn about chords, notes, strumming techniques, the fret board and chord progressions. For the bass, an aspiring player also needs to learn notes, proper finger picking, the tone of the strings and rhythm.
Instruction. Artists like Jimi Hendrix are intelligent and unique enough to teach themselves, and the Internet hosts several options for online learning. However, most people need formal instruction. Any aspiring player should search for local music instructors, and register for classes. Most instructors offer a wealth of knowledge in one to two classes a week.
Practice, practice, practice. Practice makes perfect is a cliché, but the cliché is undeniably true. Even professional musicians devoted countless hours throughout many years honing their now profitable craft. An aspiring player must continuously practice what they have learned online or in classes, in order to play whatever they write. Otherwise, a player may be able to write music, but have a hard time playing it.
Have a good idea of what kind of music to write. A player's writing will flow smoothly if he listens to different genres, has favorite guitarists and knows what genre best fits his tastes. By listening to various genres, a player can learn different elements of songwriting and playing, and can even apply some of the elements into his own playing and songwriting. A player who has favorite guitarists will likely try to emulate them. Emulation is good, as it introduces you to a style of music.
Understand capabilities. Not every player is a lead guitarist. Some players are better suited with rhythm guitar, which focuses more on writing and playing chords and riffs. A person creating a song must understand and write according to her capabilities.
Just Play. Playing the guitar is the most important step in the writing process. While playing, a guitarist will play a significant chord, riff or scale, and begin writing a song.
Write or record. A musician can either write the chord-progression on paper, or draw and annotate the chords. For drawing, six lines represents the strings, while numbers on each line represent the fret to play a string. A demo can also be recorded.
Know the role of the bass. The bass is designed to provide rhythm. The instrument's groove produces one-half of a song's necessary rhythm background, which is the backbone of a song.
Understand the relationship between bass and drums. Bass player Ed Freidland explains that understanding the relationship improves a player's ability to maintain the back beat. Since the drums provide the other half of rhythm, the bass and drums must play together in harmony.
Listen. Bassists can learn a lot by listening carefully to different music. Genres from Funk and Hip-Hop to Classic Rock and Metal all feature different playing techniques and styles. A musician will recognize and emulate the different techniques and timing.