How to create an effective first impression while submitting an online application through e-mail for sales and marketing departments?

I am a fresh graduate with almost1 year of professional experience. I am currently working in a telecom company and planning to switch into FMCG sector. Most of the time we have to submit application online through email or career portal. For us freshers, application impression plays a vital part in shortlisting as we don't have much experience. Can you guide me how to create an impressive first impression while submitting an online application through email as in the shortlisting process of a fresh graduate like me, impression of the application plays an important part specially while applying in the companies. Looking forward to your guidance;