Setting a post as the Best Answer by the original poster helps the community in a variety of ways:
Please do not feel tempted to set your own post as a Best Answer unless you reallly have a fix for the problem which no-one else has mentioned previously.
Here is a link that explains this in more detail:http://community.giffgaff.com/t5/Community-information/How-do-I-mark-a-question-as-solved-set-a-post...
1 best answer how many point
There are no set points for best answer or anything else. Points are awarded for overall contribution to the community, setting best answer to your questions though is best practice. Everything you do will affect your payback band but mostly good, helpful answers and not making pointless posts.