I've picked up this game pretty quickly, and can zip through the easy puzzles, usually in less than 10 minutes, and the medium difficulty in around 10-14 minutes. But the hard puzzles have me stumped. I only know pretty basic solving techniques.

Can anyone suggest how I can learn some more advanced techniques?

Here's an example of a puzzle and how far I've gotten. I don't know how to show this, except just to type in rows and columns of numbers. In the puzzle below, I will put the "given" numbers in bold, and the numbers I've completed in regular text. Is there a better way to show this? I also don't know how to show pencil marks. Any help you can give me on how to solve the hard ones when I get to this point would be appreciated!

6-143---8

79-682---

----1---6

46--73-1-

---1-4687

-17-56-43

5---4----

1--3-8-7-

37-5618--