Now that we covered external stimulation, we have to focus on the internal ones. It's typically the foods and drinks you put in your body that we need to cover. You've probably heard "you are what you eat" and that quote is so true on so many levels. The food you eat can have a profound effect on your sleeping, so it is important that we start to control it.
Caffeine is probably the most well known thing you can ingest that will stimulate your mind and body. You need to at least have sometime to let it digest before you go to bed. Never have soda, or coffee in the evening. Try to keep it, at the latest, dinnertime.
Chocolate will get it's own paragraph, but it's full of caffeine and sugar itself. The caffeine has its effect and the sugar will also work the same way. Your mind and body will get stimulates, so that means they won't be calm enough for sleep. As with caffeine, eat it earlier in the day.
Soda is full of caffeine, but it has far more sugar than you'd expect. It's also carbonated, so you'll be al gassed up, which isn't good for sleeping. There should be no soda in the evening because of this.
Even though alcohol can cause you to be drowsy, you're more likely to wake up through the night because you're extremely dehydrated from it. At this point, falling back to sleep will be twice as hard. Evening wine may be relaxing, but dependency isn't something you want to have, especially to alcohol.
Lastly, smoking can actually make your body wake during the night. It starts to crave nicotine more if you take it before bed. This is why you should reduce the amount of smoking you do in the evening, so you don't fall into this trap.