When you promote something for gain  (personal or otherwise) your action can be described as marketing.  The thing you are marketing can vary from a  common product or service to actually promoting your own specific skills and capabilities.

Marketing yourself can be classified by some as arrogant, conceited, pompous, overbearing and so on.  The list of synonyms related to arrogance is surprisingly large.  Humans really like to quantify that type of behavior and on the whole, it is not considered complimentary.

Marketing yourself is probably exclusively for your personal gain and this is why it could be perceived as selfish.  Our culture pretends to value selflessness although the real priority for most people is “what’s in it for me – wiifm”

Balance

Promoting yourself successfully requires not only targeted messages which convey the value and rationale your abilities provide, i.e., the reason to engage with you – but also most importantly you must not be perceived as arrogant, this would only be detrimental.

Marketing your personal brand requires not only creating an understanding of how exceptional you are but doing so in a way that displays great humility (a trait is considered of value though most don’t even know why it is of value.)

It’s not the message, it’s how it is conveyed

The balance of arrogance and humility is surprisingly easy to achieve.  The key here is not the content but rather the way in which the content is communicated.  Self-depreciating humor allows the message to be made with clarity but in a way, the recipient can accept without the danger of perceived conceit.

Along the same lines delivering the message with care being aware of the recipients reaction and stepping back if and when your target is losing receptivity.

Bottom line, don’t hesitate to market yourself but do so intelligently with care.