How to wage war like a general

The rules of combat are simple:Players, starting with black, place 1 stone of their color at a time on an intersection of lines--NOT THE SQUARES-- of any size board, usually of sizes of 9x9 (81 intersections total), 13x13 (169 total), or 19x19 (361 total). Players have an effectively unlimited amount of stones of their color (for obvous reasons you can't have an infinite amount of stones, so most people play with 181 black stones and 180 white, and if they run out they just grab rocks or something). If a stone--or a group of stones of the same color--are totally surrounded by the opponent's stones or the edge of the board orthoganally, all those stones you once owned are taken off the board and given to the opponent as "prisoners". The capturing player gains points equal to the stones of yours they capture. The ultimate goal of the game is to have the most points at the game's end. You do this by 1)Walling off sections of the board with your stones. 2)Captures. 3)White gets an additional 7.5 points, since he/she goes second. The game ends when both players pass their turns consecutively instead of placing a stone. One more rule is called "Ko", meaning eternity. This rule is that you can't repeat any position on the board that has occured before.