Do not doubt your abilities and strengths.
Do not underestimate your courage, patience, and tolerance.
Speak about yourself in high regard (without sounding like a narcissist).
Take care of yourself - grooming, personal hygiene.
Accept your faults and flaws, forgive yourself, and improve them.
Bring your best self forward.
Don't speak badly about yourself.
Don't let others speak badly about you!
Don't try to get into people's good books, or try to become part of their crowd.
Keep yourself composed, don't lose character.
Don't sell yourself cheap.
Appreciate your uniqueness and don't be shy to express it.
Don't trust your heart with those who don't value its worth.