Relaxation is key to an orgasm. If you're worried that someone can hear you or that the kids will come home from school, you'll be too tense to truly enjoy yourself and let go to orgasm. So schedule some "Me time," lock your door, and turn on some music or other white noise to help you let go.
Arousal is also important when it comes to orgasm, but a woman's arousal doesn't necessarily work the same way it does for a man. You might be accustomed to the four stages of sexual arousal, which put mental desire before physical arousal. But a woman's desire can lag behind arousal. This is precisely why you might get in the mood only after activities have started.
Whatever it takes to get you in the right headspace, do that. For some people it's wearing lingerie, others prefer a glass of wine. Erotic media such as porn or a steamy story works for others. If you're focused on partner activities, get the ball rolling with a few sultry texts, perhaps with pictures.
The more aroused you are, the better stimulation will feel whether it comes from a partner's fingers or mouth or your favorite vibrator. This leads us to our next point.
Don't be afraid to use tools. Many women can get more intense G-spot stimulation with a dildo that has a bulbous head. Others find it much easier to orgasm when they have the assistance of a rumbly vibrator. There's nothing wrong with you if you find it much easier to orgasm when you use a toy or if that's the only way you can orgasm.
Many women -- and sometimes their partners -- worry that something is wrong with them if they don't orgasm from penetration alone. But most women need direct clitoral contact, so rub your clit or use whatever tools are available to get that orgasm! Try circular movements, up-and-down or side-to-side. Some women prefer indirect stimulation through their underwear or even labia rather than touching their clitoris head on.
Communication is vital when you're with a partner. When you're by yourself, you can take your time to focus on what you like and adjust your technique, but your partner can't tell what you like. So it's up to you to provide that instruction. Otherwise, you'll have a hard time enjoying yourself at all let alone having an orgasm.
Our final piece of advice might seem counter intuitive. Don't try to focus on having an orgasm. Instead, focus on the pleasure. If you're too goal-oriented, you might not have an orgasm. But when you enjoy the moment, you'll feel like your time is well spent even if you don't have an orgasm.