The word Buddha means "enlightened being". Everyone has Buddha nature so everyone can become a "Buddha".
There are two ways in achieveing enligthenment: Become a Buddha or become an arahet. Arahats are those who practise and medition by ways of retreats. These hermits' priorities are to attain self-realization first before helping others. In today's world, becoming an Arahat is seen as impossible due to our very clouded mind.
On the other hand, A Buddha strives towards enlightenments while helping others and propagating dharma (Buddhist teaching). This channel of becoming an enlightened being is the one that is preached in this world.
To become a Buddha, you will have to practice through meditation, studying sutra, practising mantra and of course help others in need. All of these will contribute to the good karmic forces which then give you(and you only) good merits. These merits can be saved, or transferred to someone alive or deceased.
Being a Buddha, you must have perfect compassion and perfect wisdom. Self-realization is emphasized because it leads you to Nirvana.
To keep it short, you can start practising in this life and maybe in one of your future lives, you will be enlightened! (It will be long though...because we are 8000 years away from the end of this dharma time. Then Buddha Maitreya will propagate Dhrama. It runs in a 12000 years cycle).