I have noticed that my credit score is not increasing. Is it normal? What to do to increase score?

Living your financial life in a unhealthy way can cause that. First, let us know a thing, did you get a drop on your score or it is constant?
The first thing you should check is your credit report. There might be some errors, or you have a negative item added there. It might also happen that you recently closed an old credit account or you are currently using too much of your available credit.
Make sure that you aren't facing an identity theft issue. These things might make your score stagnant for a while.

Credit score doesn't increase all of a sudden. To increase your credit score, you need to manage your credit cards properly. Stay within your credit limit. Also, repay your bills in full and within time. Don't close your credit card accounts. With time, you can see changes. However, if you see there is no improvement, check your credit score to find out wheathe ror not there is any wring listing. If you find the wrong information then dispute it.

As SandersPatricia said, use your credit cards wisely. Charge your credit cards for small amounts. And pay off your outstanding balance amount in full and always ON TIME! Besides, don't max out your credit cards. This will help you to improve your payment history and credit utilisation ratio low. Hopefully, you can see an improvement in your credit score. But don't expect your credit score to increase within a flash.

Your credit score can remain static for various reasons like:

You have used much of your available credit
Your credit report contains a negative item
Your credit mix is not diversified
Hard inquiries are there on your credit report
You have become the victim of identity theft

I would like to add to what Craigh has said. Along with managing your credit cards responsibly, try to have mixed loans like installment loans, revolving credit, etc. It can help you to boost your score. And, check your credit scores from the major 3 bureaus at least. It may happen that the credit score you're checking, that credit bureau might not have the information of your every financial transaction.

i have unwanted collections ,late payments , tax liens and of course charged off accounts , i have tried many means to get my profile back and have my score up excellently ,it happened just like magic when all unwanted collections, late payments ,tax lien were removed and increased my credit score from 416 to 806 .i don't believe at first until it all happened . ever since then i have been having a perfect credit profile.