How to increase your brain power:

Your mind, like your body, needs exercise in order to function well. A few ways to exercise your mind is to  do some crossword puzzles, or play common games like solitaire or chess to keep your mind sharp.

Keep on adding, multiplying, and subtracting. Do not always depend on a calculator.

At least once a week memorize a poem, a joke, or a psalm. This will help to keep your mind in shape, and will increase your brain power in time.

Learn to think inventively. Let new ideas come forth. A good hint is to think as a child. They think with creativity, wonder and curiosity: allow yourself to daydream, as this will increase your brain power and keep a sharp mind.

Do not limit yourself to being one type of person. Be many persons! Think in as many ways as you can.

Keep a pen and a paper in every room of your environment so that when you think of an idea you can jot it down immediately.

Do not be afraid of making a mistake. Nobody is perfect, and never will be. Learn from your mistakes. Do not be afraid to try new things.

Trying new things lets your mind wonder and lets your creativity come out, and everything that you have practiced will be shown.

Talking to yourself may sound silly, but it works! It is a very good memory aide, to help you find something when it is lost etc.

Keep close watch of upcoming events or family get together. Discuss them with friends and family.

Tension can interfere with memory, so learn to relax. This will help you think more clearly.

Good nutrition also keeps a sharp mind.

Remember as many names as you can, and put a face along with the name. This will surely help your brain power improve.

Do not drink too much alcohol, this impairs memory.

Depression is often a cause of memory loss. If you are depressed seek medical advice and attention.

To spur creativity talk to encouraging, not discouraging, people. The best thing to remember and live by is to exercise your memory and your mind.

Try new things that may not even interest you. Find new people to talk to, or go out to a new restaurant. Do not fall into a rut, do not always do the same things one after another.

Brainstorm, and write things down as you think of them.

Study new subjects or languages. Before bed is a good time to do this.

Relax. Maybe even take a bubble bath and play some soft music. Everyone needs to take time in their busy day to relax, this also increases brain power.

Dream.

Read a book. Reading helps the mind, and memory.

Physical exercise is also very good for the mind. Do an aerobic exercise, or take time out to go to the gym.

Take walks. This lets your mind rest as well as think up new ideas etc.

Take on a new hobby, such as sewing or playing pool. Do not ever limit yourself to one thing. Do not be afraid to lose.

Stay focused when you are introduced to a new person or persons. Clear your mind of other thoughts. Do not preoccupy yourself with other things, this may cause you not to hear the other persons’ name etc.

Have a set to place your keys, gloves, jewelry etc.. This will make a safe place for them, and have them not to be lost, and you will always remember where they are at.

If something is bothering you, write it down. Keep a daily journal and write in it daily. Another good idea is to keep a dream diary, every dream that you have write it down.

Have a place to write down your yearly, weekly and daily goals. Work on accomplishing them.

Brain power increases as your daily activities increase. Do not depend on other people, or items such as a calculator. Keep your mind sharp.
Reference: http://girishk.com/2007/04/25/how-to-increase-your-brain-power/