Given its importance, the prospective groom will want to take some time to think about how to make the wedding proposal memorable. This means that a smart groom will carefully plan what he is going to do and avoid any impulses to spontaneously propose to his girlfriend.
When you are planning the act, you should take some time to think about your partner's personality. Is she an extrovert or an introvert? Without getting too deep into psychological analysis, you need to determine whether your girlfriend would appreciate a huge, potentially very public display of affection or would she rather have an intimate moment alone with you. That being said, it is up to you. If you are confident that the outcome will be positive, put as much creativity into the proposal as you feel comfortable. Regardless of the tone of the proposal or the amount of creativity involved, you do not want your proposal to be overly complicated, unless you are prepared for things to go wrong.