Stain issue

I am 21 years old living in India and going start my career as a market researcher by end of this month.

Well in my company no one in the team and immediate boss wears a tie and suit.

I am guy who cannot save his light colour T-shirt from stains. So, what should be my first five dress shirt?

If I can wear only dress shirt, trouser and oxfords

Well in my company no one in the team and immediate boss wears a tie and suit. So, my weapons to look sharper are only limited to my dress shirt, trouser and shoes. What type of dress shirt and trouser should I wear?
If I just consider to wear solid and stripes pattern dress shirts along with solid light textured wave trouser and black Oxford shoes. Do you guys feel it will turn out to be sharper? This is my confusion and biggest problem to dress sharper.

Thanks
Hemang