Self-promotion can be hazardous for some and effortless for others. There is an invisible line of self-promotion that some see well, while others go over with reckless abandon like a speeding driver on an icy road [an accident waiting to happen].
If you have to think about how you're going to promote yourself, then you might need a professional to help you determine what your strong points are based on your objectives/goals. On the other hand, if you ooze with confidence, you're the life of the party [without being overbearing] or have experience in a particular subject matter, self promotion comes naturally.
However, there are those moments were we want to shine brightly but have anxieties or others deficiencies that hinder us from truly being the best we can be [when it counts]. Even the best speakers, performing artists or persons in leadership know that we must ALWAYS be self promoting to gain [or maintain] the confidence of those we interact with.
Often, self promotion is associated with "selling things" but that could be farthest from the truth. When people buy from YOU, it's really not the product they are buying. They're purchasing from you because of your ability to confidently "self promote" yourself, the organization and whatever product or service you're merchandising.
Self-promotion is not about "pushing products" but about being the REAL you. Not the person selling Brand X or your book/music. Its about letting people inside and discovering what makes you tick and the wonderment of discovery when we're introduced to a dynamic personality.