Essentially growing a more secure attachment style comes down to create a stable life with stable relationships as well as increasing your inner stability through practices that support it:
- embodied practice (yoga/meditation/exercise)
- reducing addictive behavior (drugs/coffee/porn/etc)
- reducing clutter/distractions
- increasing self-esteem (the book "The Six Pillars of Self-Esteem" is great and has practices in it too)
Also you can look at increasing stability in 7 different areas:
- Physical (good/enough sleep/food/water/exercise)
- Spiritual (good/enough meditation, prayer, ritual)
- Somatic (good/enough movement, dance, etc practice that involve the 4 pillars of embodiment: touch, movement, sound, breath)
- Emotional (good/enough solid/secure/fulfilling/supportive/connection with friends/family/mentors/allies who are themselves preferably secure. Therapy is an example of a secure relationship with mentorship)
- Social (good/enough interactions with peers/community that make you feel connected to the world so you don’t isolate)
- Primal (good/enough engagements with nature and the world that allow you to feel and feed your inner animal)
- Intellectual (good/enough reading/conversations/learning that allow you to know yourself and others better over time)
Also along with the practices and skill building above:
- Coming up with a purpose/vision in your life
- Have a peer-group (other people with a disorganized attachment style to be in conversation with)
- Have a community who is supportive (and you can relate to) around the above inner/outer stability and practices.
- Have a support person (coach/counselor) who will lend you their compass/stability/perspective while you grow your own
As someone who is now consciously secure (ie moving from 1. unconsciously insecure to 2. consciously insecure to 3. consciously secure) and with partners who stabilize me, I find that I have more space for those who are insecure in my life.
In other words, if emotional security is like emotional balance, my sense of it has become better with time (more conscious) and my partners and my son add to this balance too, and I can give it back to them and others from there.
I think the same is true of how we gain emotional balance through our work/career, friendships, self-care, self-love, and more.