When I returned to the Church I wanted to be involved in some way in the life of the Church. When I left the Church I was on the fray and not at all involved. Then again, I didn't bother to see what the Church had to offer. Hindsight is great! There was and still is so much to do to become an active member and feel a sense of being a member of the body.
At the parish level there are lots of ways to keep involved in the church. Just read the Sunday church bulletin. Ask for a list of parish groups to see what piques your interest. On a wider level there are other organizations that need support and your help. I joined the Knights of Columbus to help out the community.
If you feel called to form your spiritual life with a bit more structure, there are many secular third orders and associations that meet and form their members in a path to seek God and follow Him. Some of the more popular secular orders are the Secular Carmelites, Secular Franciscans, Oblates of St. Benedict and the Dominican Third Order. There are Formal Catholic associations that follow rules of life. The one I belong to is The Brothers and Sisters of Penance of Sy. Francis. We strive to follow the first Rule set forth by St. Francis for his secular followers. This rule of life is known as the Rule of 1221.
Depending upon where you are at in life and where you feel you are being led will certainly contribute to what group or organization you will become involved with. But I cannot stress this next thing enough... before you choose a place to involve yourself, pray first! Prayer is our "go to" source of advice and help. God will guide us to just the right place for you and for me. Realize, too, that there each pathway and organization has some limitations and each has areas where you may struggle a bit. But if you seek the right path through prayer, God will go e you the necessary grace to stay with it.
One final note on this, remembered to keep your eyes on Our Lord, Jesus Christ I whatever direction you go!