You asked

What can I try to get my child to sleep without hassle?

Parents who are able to get their children to sleep successfully on most nights, all have similar routines. It is important to set a definite time for bed and not to deviate from your routine too much.
Your bedtime routine should comprise of calming activities, to relax your child's mind and body and make falling asleep easier.

After your child has had supper, avoid energetic playing, but rather have a few minutes of television or reading. Follow up this low-key activity with going to the toilet, or doing half a nappy change before bath. With your child clean and changed, assist with proper brushing of teeth and changing into pyjamas. This ordered routine is predictable and lets your child know that bedtime is coming up. The bathing and cleaning will make your child feel comfortable and sleepy.

When you take your child to their bedroom, make sure the lights are not too bright. With your child in bed, or in their cot, read a bedtime story, sing a song, or play soft music to help with relaxation.
Tell your child about the next day's activities that they need to be well rested for. Convince your child that the sooner they go to sleep, the sooner they can wake up and enjoy the next day.

More questions

Nightmares generally occur in the middle of the night or in the early morning. 
When is the right time to move your toddler from the cot?
 Up until 2 years of age, a child needs about 14 hours of sleep a day, most of which should be at night.
The best way for your child to sleep well is to develop a daily routine
If you can’t get your toddler to sleep through the night then it may be necessary to adjust his or her nap times during the day
Different children nap for different lengths of time at different times of the day but the most important factor is daily routine and consistency
There are many reasons you’re toddler may not be sleeping but also many simple solutions for this frustrating problem
When and how to make the transition from crib to bed
Benefits of having the right lighting in your little one’s room at bedtime
A guideline to knowing how much sleep your child needs and ensuring he or she is well rested