How do you guide your children to have good study habits?

i think it's important for children to develop good habits from a young age and parents should help them get started. maybe when the child is 5-6 yrs old is a good age because it gets harder as they grow older. don't start them too young tho; young children should first enjoy pre-school so that they get a positive attitude towards schooling. agree on a specific study time and place and make sure that there are no distractions. at the start it may be better to closely supervise them then slowly you can leave them on their own to show that you trust them to do their job.

we can just motivate them to do well and encourage then..

I believe it is equally important to teach our children the attitude towards study. It is not so much on whether the environment is conducive for study although it helps a great deal to have one. Even if there isn't, it is the determination to turn around the situation and make value out of it. I've known many poor families do not have proper study furniture, they have to do their studies on the floor or bed, yet they achieve outstanding results. They want to prove to people that even under unfavorable circumstances, one could still achieve something. On another hand, parents would need to gain the trust of their children, be their partners in the study journey, giving encouragements instead of demands and orders. Parents and children must be like good friends. Thus it would help to work out a proper study schedule with the kids, such as study for 2 hours, take a break, study for another 2 hours, then allowing them to watch 1 hour of TV and 1 hour of games. There should be some incentives and some rules firmly set in place. In this sense, both parties will enjoy the process. Since the children are pretty smart these days, it is almost impossible to remove every source of entertainment and only give them a pure study environment. They would think you're trying to challenge them and they'll try every means possible to circumvent it. Thus I believe the wisdom of parents to reach an agreement with the children and knowing when to come in and when to step aside is crucial in achieving a win-win situation.

The youngest is easier. It's being there to support him personally. Answering his many "Whys?" Read stories and listen to him. Play with him sometimes. Allow him the many breaks he wants and each time telling him the more breaks he has the longer time it would take him to finish his work, tell him about choice and its consequences. The older ones are different. Talk to them and let them think of where in the house they can study best. Try to provide them that comfortable environment with tables, chairs, good but not too glaring light. Keep away the things that can distract them. I suggest to them ways to study: make a schedule, establish a study routine, make a list of things to study and to put a tick against each item once they have completed because that would give them a sense of success and achievement. Talk to them to start with the easier ones or the ones that interest them a lot. By regularly catching up with them on their studies and how things have been going on for them make them happy. When they do, I'm a happier dad as well!