Using female sex toys can be tricky if it's your first time.   You're bound to be nervous and self-conscious, but don't worry: it's really quite simple, and it only gets better with practice.

Before you even start using your sex toys, you should prepare for it.  Make sure you have your toys and your lube (if you plan to use it) handy.  Get yourself in the mood by doing something that arouses you, like watching an erotic movie, fantasizing or reading a good sexy book.  Don't move on to using the sex toys until you feel that you're good and warmed up for them.

There are many parts of a woman's body that can be stimulated with female sex toys, and which ones you choose to play with will depend on your tastes and also on what toys you have.

Vibrators are particularly good when used to stimulate your clitoris – and many of them have the added advantage of having multiple speeds, allowing you to start off slow and work your way up to a greater level of intensity, or just go hell for leather from the very beginning.  Take care, however, not to over-stimulate your clitoris, as the results can be painful – the more sensitive your clit is, the less time and possibly the less speed of vibrations will be enough to bring you to orgasm.

Locating your g-spot can be a tricky process, but it's well worth the effort.  Dildos and vibrators are the best female sex toys for stimulating the g-spot, and both of them will also pleasantly fill your vagina when in use, making for a richer sensation.

Even without stimulating your g-spot, penetrating your vagina with a vibrator or dildo can still be very enjoyable – and you can do it in positions you never could with a man, since the imitation penis isn't attached to a body to get in the way.  Some dildos and vibrators come with mounts (suction cups, for example) to allow you to firmly place them against another surface before penetration.

Although it's not to everyone's taste, many women also enjoy anal stimulation.  Smaller female sex toys such as anal beads and bullet vibrators may be more comfortable in the anus than a regular sized vibrator or dildo, and always be sure to be sufficiently lubed before attempting anal penetration.
 
Don't forget your breasts, either – especially your nipples.  There's no vibrator specifically designed for use in stimulating your nipples – the manufacturers of female sex toys seem to have unaccountably overlooked this particular sexual arena – but holding nearly any vibrator against them is likely to work pretty well regardless.  As with your clitoris, take care not to over-stimulate your nipples.

Finally, some women also enjoy simulating oral sex with dildos (and sometimes vibrators, but most people find the rattling sensation in their teeth unpleasantly reminiscent of a dentist's drill).  The only real issue with this practice is the size of the female sex toy you use for it – you do want to keep breathing, after all.