I have heard lots of advice on this topic and I'll just repeat what I've heard.
1) Never strike your shins with anything. It cause bone bruises that don't heal.
2) It is ok to roll a stick (rattan) up and down your shins. It will bring results (slowly) but it will help as an add on exercise. Usually start with about 100 rolls, and work your way up with reps and intensity of pressure on the shin. Make sure to point your shins to fully expose the shin bone and roll it on the point of your shin not the flat sides.
3) The only tried and true thing that works is kicking a solid heavy bag and thai pad training. This takes a long time, but it gives results.
4) Don't rush it. You will get injured. Like anything else, it takes time, hard work, a decent pain threshhold and determination.
Good Luck
tom