让我们改进您的示例-注意备注

// You are using 2 different Font sizes, so let's create reusable instances:
var fontBigBold = new Font("Century Gothic", 12, FontStyle.Bold);
var fontNormal  = new Font("Century Gothic", 8, FontStyle.Bold);

// Let's shorten the Brushes, too for Readablity
var crimson = Brushes.Crimson;
var blue = Brushes.Blue;

// let's have the computer compute, not our brain.
var linePtr = pos + 50;

e.Graphics.DrawString($"Grand Total: £ {grdtotal}" , 
               fontBigBold , crimson, 
               new Point(60, linePtr)); // <-- you already were on the right track!?
linePtr += 35;
// \n does nothing for you! Let's ditch those.
e.Graphics.DrawString("***The Android Dungeon***", fontBigBold , crimson, new Point(40, linePtr));
linePtr += 35;
e.Graphics.DrawString($"Thank you - {CusName.Text}" , fontNormal, blue, new Point(40, linePtr));
linePtr += 35;            
e.Graphics.DrawString($"{Addresstb.Text}", fontNormal, blue, new Point(40, linePtr)); 
linePtr += 35;
e.Graphics.DrawString($"{Postcodetb.Text}", fontNormal, blue, new Point(40, linePtr)); 
linePtr += 35;
e.Graphics.DrawString($"{towntb.Text}", fontNormal, blue, new Point(40, linePtr));

为了简单起见，我在这里假设行高为35，如果只是行高的话，我可以用MeasureString加上一个“M”来得到行高，这很有趣。
像这样

int lineHeight = (int)e.Graphics.MeasureString("M", fontBigBold).Height + somePadding;

进一步改进：

• 我会尝试重构，这样重复的部分就在函数中，而这段代码可以专注于实际用途。
• 我会再次使用MeasureString来确保字符串不会变得太大（太长）。对于这种情况，你可以想到不同的解决方案，如省略号或换行......由你决定。