To begin with后面要加逗号。 To begin / start with表示"首先",在句子中作独立成分，需要用逗号和句子隔开,举例如下:
To begin with, we must consider the matter all-sidedly.
To begin with, we must work hard at our lessons and be fully prepared before the exam.
加上to begin with这样的表示逻辑关系的词语, 英语作文会变得更加有条理。
表示逻辑关系的词语还有 Furthermore, besides in addition, finally等等。
