In life, there is what we call birth and death but in between this is growth. No one was born old, we were all born as little children and grew up into adult then we will all grow to old age. So growth phase is one whick cannot be neglected.
There are things that little children cannot do as a result of their age, and till they grow up to certain age they might not be able to benefit from it. So it is evident that everyone grows up. If a baby remains an baby, he or she will become a concern to the parents and people around. When it is time for a child to walk, if that child is still crawling it becomes a concern.
For when for the time ye ought to be teachers, ye have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat.  For every one that useth milk is unskilful in the word of righteousness: for he is a babe.  But strong meat belongeth to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil.
So as Christians you are expected to grow up spiritually, you cannot remain a baby christian for ever.
After giving your life to Christ, there are certain things to do in order to grow your spirit man. A child who doesn’t feed on healthy food will grow abnormally especially if the major nutrients required are absent. So you need to engage yourself in things that will help you to grow up.
What should I do in order to grow up spiritually?
1. Be born again : this is the first stage of spiritual growth
2. Feed on the word of God. The word of God is the food of the spirit. Jeremiah 15:16
3. Listen to sermons: Learn from other ministers who have gone ahead of you.
Not only should you read also listen because faith comes by hearing… Hebrews 10:17
4. Read books: there are alot of insights in the pages of other people’s books, many men of God have written down their personal discoveries from the scriptures into books with different titles, so get books related to the questions in your heart and read
5. Have spiritual mentors: There has to be spiritual fathers you look up to, let them guide you and also monitor your growth
6. Be mindful of your circle of friends: if your friends are not more spiritual than you, you are probably not growing enough because you will be the one always pouring out your knowledge to them. The Bible says iron sharpens iron (proverbs 27:17) so choose your friends wisely. 1 Corinthians 15:33
7. Sieve what you ‘hear’ and ‘see’: don’t allow just any content into you. You are a product of what you see and listen to. They are like seeds growing in you, one day you will reap it’s fruits.
8. Pray regularly: when you pray, your heart will be focused on God because of the regular fellowship, with this, you will be interested in the things of the spirit and this will hasten your spiritual growth.1 Thessalonians 5:17
9. Be a doer of the word:
James 1:22 KJV
But be ye doers of the word, and not hearers only, deceiving your own selves.
Don’t just read to know, also put the word to work.
10. Meditate on the word: ponder on the words you read in the scriptures. Joshua 1:8
It is by meditating that you get deeper insights in the word
11.Believe, confess and declare the word:
Romans 10:8 KJV
But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;
When you keep confessing the word, it will register in your mind. You will get familiar with the word, you will remember them at the time you need them.
12.Dont neglect the gathering of believers: don’t frown at Bible study and prayer meeting with other believers, you will grow better by also learning from them. Hebrews 10:25.
So with this few points, if you follow them faithfully, you will scale new heights in your spiritual growth.