Similar to how I do it. I usually sub off anyone who has a yellow card, though maybe not instantly, if they get it in the first half I wait until half time. If they get it in the 2nd half I take them off straight away. If my opponent is really tough I try not to make 3 subs because usually I end up conceding. I just tend to replace 1 player who isn't playing well and throw on another striker or an extra defender depending on the situation.