Depending on how damaged your hair is, you will generally want to cut just above where a majority of your split ends are, 0.5 in (1.3 cm) or so. This will cause your hair to be much healthier and will help you to maintain your locks. Worry about getting the hair styled and shaped after you've done the damage-control of getting your split ends taken off. For curly hair, you may be able to wait up to 8 weeks to get it trimmed, but most other hair types will require trims every 6 weeks to keep their hair healthy. If you are uncertain on what style you want and are not happy with what has been advised or do not think that it will suit you, start by cutting your hair inch by inch. This way you can tell how short is too short. Don't try to get it over with and chop the hair off in a few seconds. Take your time.  Measure off the hair accordingly and hold the hair straight in between your fingers. Cut in a straight, even line with no angling if you want a blunt cut. Hold your hair at a 45 degree angle your hair if you're going for a bob. For layers, clip off the hair being used for the next layer or so in sections. Remember that you can always cut more hair off, but you can't put it back on! You don't want to cut straight across your hair, but make short diagonal snips when you've got your hair about as long as you want it. This helps to keep hair looking healthy and flowing, rather than lank and flat. You want to avoid making long, straight cuts on your hair, or it'll look flat and dull. Remember, your hair will dry and won't be as straight (even if you have very straight hair), so there's little point in worrying about getting all the ends the exact same length. Hair looks dynamic when the ends are "evenly irregular." Often changing from long hair to short hair can be such a change that you may not like your end result at all. Often the change only seems bad to you and it can usually take up to a week for the hair to grow to a nice length or for you to get used to it. Try to style it in a few different ways and...

TL;DR in Indonesian:
Mulailah di ujungnya. Potong sedikit demi sedikit. Potong pendek-pendek secara diagonal. Berikan waktu beberapa hari lagi.