How to get my teeth white again?

Bleaching trays: I would recommend dentist made custom bleaching trays that are made to fit your teeth. The dentist will prescribe a bleaching gel that you can use in these trays at night. This is the most economical and effective way to whiten teeth. Don't waste your money on mouthwashes, gums, and toothpastes that claim to whiten. Otc bleaching strips work pretty well.

Depends: This depends on the reason for the discoloration. Stains and age can cause this, but so can cavities, trauma, and periodontal disease. I would see your dentist and ask his/her opinion. It may be as simple as whitening with trays or an in office procedure, or it may require something more drastic like veneers. Without seeing your teeth, it is hard to say what will work best for you.

Prophy & Bleaching: Do your best homecare and get your teeth professionally cleaned. From that point you can either get an in office bleaching or have impressions taken for bleach trays. Hopefully the results will be to your liking, if not, lumineers can be a great option.

Whiter teeth?: Step one: use a whitening toothpaste but only short term as it is very abrasive. Step two: get a professional cleaning if it has been some time since your last one. Step three: make sure you have no cavities and your gums are healthy. Step four: ask your dentist what your whitening options are, both professional and at home methods. Decide what is best for you. Other options also available. Ask.