Ok, I'll try to break it down the essentials. Good brands are: Brooks Brothers, J press, J crew, Orvis, LL Bean, Polo Ralph Lauren, Barbour. I believe you should also take a look at Patagonia. Oh I nearly forgot, kamakura shirts in new York have good shirts and ties. There are plenty of English brands as well but I can't recall the names. There is one where I get my suits from when I'm in London. I think it was B something.
Buy Oxford shirts, essential colours are white and blue. Buy flannels from LL Bean.
Get some nice sweaters in many colours. Cable knit sweaters are also important. Maybe even get sweater vests for wearing under blazers. Cricket/tennis sweaters are also nice.
Pants are good to have in many colours but the most basic and essential is to have khaki coloured chinos. Get a pair of nantucket reds.Corduroy pants are good too. For summer and spring you should get a pair of madras pants and shorts. In a category of their own are go to hell pants. They can be fun, look them up.
Spring is here and summer is approaching. Buy polo shirts in as many colours as you can. Seersucker is a good material for warm weather, so get a pair of seersucker shorts.
For spring you should probably get a Harrington jacket. Barbour wax jackets are also good. Personally I don't like vests but I suppose if you want to you could get vests.
It is important to own a nice pair of loafers, perhaps bass weejuns, they are not expensive. Also buy a pair of boat shoes. For rainy weather and such you should have a pair of LL bean boots.
Get a navy blazer from Brooks Brothers, a grey tweed blazer, and for fun get a seersucker blazer as well.
As for ties, many different ties work. The repp tie is essential though. Knit ties are cool too. If possible get a tie with your university's colours or emblem.
I don't recommend to buy everything at once, find what fits you the best.
Now that's basically what I can come up with quickly, probably a lot of stuff I left out.
