1.“By recycling,processing on second-hand goods,then sold them at a low price relative to the original prices of goods“ 这句缺主语的,你看这样可好：After recyling and processing on the second-hand goods,I sold them at a relatively low price compared to the original prices of brand-new goods.
2.These practices do not only greatly improve my bargaining skills but also give me confidence to have deeper understand on the field of finance.这句太罗嗦了.可否改成这样：these practices not only improve my bargaining skills but also provide me deeper understanding on marketing.个人觉得你写的是营销不是金融哈.所以改成marketing了