I want to whiten my teeth, kinda yellowish, can u suggest some tips. Thanks?

Teeth whitening. You can use OTC tooth paste or crest 3D whitening strips or pens. However, they are not so effective and/or stable. OTC bleach and whitening tooth paste could be used as a supplement only. A professional teeth whitening without laser, followed by home whitening system with custom trays for the long term effect. You will be very happy with the results.
Professional only. Professional bleaching only. Don't waste your time or money on over the counter bleaching materials that do not contain the same percentage of peroxide based material that professional bleaching does. In addition, the dentist can alter the percentage of bleach based upon need and individual circumstances and a custom tray is provided not a stock tray or strip.
Sure. Make sure you are brushing thoughtfully twice a day, avoid staining foods such as coffee, tea, or cola drinks, make sure you are getting professional cleanings at the recommended interval and after all that, explore OTC bleaching such as White Strips. If that does the trick, you are good but if not, be sure to inquire about other dentist-accomplished options, of which there are many..