Most would agree with me when I say that, us as a society sets a standard for everyone to follow. To be "this" you have to follow & perform "these" steps. As with a mature person - someone who is looked at in a respected manner, it's that IT factor. Most people who know when a person has matured would say, he gets "IT." Nowadays, we see this word being tossed around like it's lost its meaning. Lets clear some things up, an elder person should NOT automatically be considered mature. Maturity does come with age, but it's far from a sure thing. Someone who can support him or herself financially should NOT automatically be considered mature. Being financially stable is a great luxury to have but just because you are able to pay off your expenses does not mean your "mature." People who seem to have this sort of a perspective of what exactly is a mature person should reconsider their thoughts.
So to finally get to my point, you can be mature in more than just one way. There is no real blueprint but if you do some of these next few things, your in good shape. Being mature is taking responsibility for you actions, having common sense, having the ability to love, forgive and respect others, telling the truth, thinking about others prior to thinking about yourself, giving for the sake of giving and not expecting anything in return and last but not least, contributing to society in a positive way. So if you feel as if you need to be more "mature" person, performing some of these activities would be a good start.