That's an absolutely huge question. I am a big fan of this grammar resource: http://dictionary.cambridge.org/ You can also check a normal dictionary most of which include example sentences. Then check a sentence database like fraze.it Once you have some ideas you can try creating your own sentences and then ask people to check them for you.

I went to sleep, even though I wasn't tired. I just remembered that I have a test tomorrow and I didn't study! The only thing I want on my sandwich is ketchup. All the employees are dressed similarly. Not only is he funny but he is nice also.