You also tells about the BMI or BMR to know about your right and stable weight.I recommended you this Weight Loss Calculator to get the appropriate right weight calculations.
How much you should weigh based on height and age isn't really set in stone, it's different for each person. However, if you think you're overweight it's a good idea to calculate your Body Mass Index.
As for dieting tips, here's how I've had success: Portion control! It's the biggest mistake people make, that they don't realize they're making. If you limit the amount you eat already, then I would try making minor changes, like cutting out soda or sugary drinks, and eliminating a junk food or two from your regular diet. This usually does the trick! If you include exercise, even if it's just taking a walk around your block, going the long way at school, or getting involved with a sports team, the weight will come off much faster.