Chicken Grilling Help

"I often eat chicken breast for my whole meals. I have a small charcoal grill which I use most frequently to cook this. I am currently in smaller country in asia, thus I do not have the fancy equipment that some of you may refer to :(

My grill is basis, you put the charcoal, heat up the charcoal and there it is. There is a grilling rack I put on top of the charcoal.

I usually put a 250gm Boneless Chicken Breast on the grill, however, by the time I am done cooking it the outer breast is really hard like leather.

The inside meat is fine, but I just get the feeling that maybe I am doing something wrong. So many times when I eat out in restaurants, I get a tender chicken breast, which is white/cream in color with those lovely charcoal grill line markings.

I wonder what I am doing wrong...any tips on how to cook up a great chicken breast on a charcoal grill?

Also, I am really limited in terms of good chicken recipes, marinades, I would appreciate any suggestions please."