#2. Gauge Her Level of Interest. It’s possible to get some idea of how well things will go for you before you’ve so much as spoken a word to the girl you have your sights set on. It’s best not to go in cold, so spend some time gauging her level of interest in you ahead of time by paying attention to her body language and nonverbal cues.
Have you spoken to her before and, if so, how well did the interaction go? What was your level of rapport like? Does she make sustained eye contact with you and touch you where possible? These are all indications that she’s interested in you on some level, so try to pay attention to these details before you make your approach.
#3. Make Sure the Scene Is Conducive to Success. When you decide to approach the girl you’ve picked, the setting needs to be conducive to success. It can be embarrassing, for example, to ask a woman out if her friends or family are around and within earshot, and likewise if she’s busy doing daily activities like commuting or shopping for groceries — it’s likely she won’t want to be disturbed in this case, and you’re more likely to get an annoyed “no thanks” when you ask in inconvenient settings.
The ideal setting is going to depend somewhat on how well you already know this girl and where you tend to run into her most often (through a circle of friends versus occasionally bumping into her at your local bar, say), but try to be conscious of asking her out in an environment where romantic advances are likely to be welcome. Make her feel comfortable and be respectful, and she’s much more likely to want to spend more time with you.