Masturbation-need advise

I'm sure it's a bit different for everyone, but personally I would suggest masturbation to all married couples. If you know yourself well enough to be able to say exactly what pleases you most, you can then share that info with your partner, which results in more satisying experiences for both.
As a couple, we actually enjoy masturbating together sometimes, because we both find it arousing to watch each other. One or the other of us sometimes performs it alone as a means to tease each other too...a form of foreplay if you will, like if you were to dance erotically for your partner. And it does take the stress out of those times when you're apart or your partner isn't in the mood for sex.
"How" is entirely up to you. If you've never done it before, you might feel more comfortable trying it alone a few times though because you'll be more able to pay attention to what feels good if you aren't thinking about your partner's reaction.

Why should we convince you to do anything? That's ridiculous. If you want to do it, do it. If you are perfectly happy with your sex life as is, don't. Simply put, the fact that you even posted suggests that you want to do it.

So how? Well, focus on a sexual zone. Clit, vagina/g-spot, anus, breasts, or any other specifically arousing place. Then it's up to you. Vibrations work well for many women. You might try rubbing, pinching, swirling, tugging, tapping, thrusting, grinding (against), pumping/suction, water from the tub faucet or shower head, humping a pillow/blanket, so on and so forth. There's really no right way. Maybe just mimic what your partner does to you.

Ok...first, Adriana's right. If you ask, you are interested.

Next, does your husband like porn? If so, there is a good chance he would like to have his own personal porn star.

Walk right up and ask "would you find it hot to watch me masturbate?" Let him know you're curious. I am almost positive he will drag you down the hall to the bedroom and tell you to get to it. As a general rule, husbands try not to "upset" the wife with requests she may find offensive, so they look other places.

We should not be convincing you, you should ask him. If it turns him on, try it out for him, that alone should convince you.

As for how, that all depends on what turns you on. For me it is all clitoral (I am working on the whole g-spot thing, but I think I need a tutor or something). Some girls love the g-spot, others are nipples. If you are not keen on manual masturbation, get a vibrator (EF has lots of those!) or you can look at other toys. I have known girls who only do it in the shower, some set a mood with candles and music and all that. I am also guessing you were never taught that masturbation is healthy. It is, just like breast exams. Right now there is a good chance your husband knows your nether-regions better than you do, that needs to change. You should know what you like, if you don't then get to exploring. I bet you will find some really interesting things out about yourself.

Invite your husband in on it if you are nervous. He can guide your hands as if her were using his, this may make it a little easier on you. There is no right or wrong way to masturbate. I promise

I find the more I masturbate, the more my appetite for sex in general increases. So if you find your desire for sex with your husband waning, this might be a good way to combat that. Also, knowing how your body responds to different forms of touch can only help you help your husband improve his ability to please you.

Now, how to start? Start like most of the rest of us did, explore your body and when you find something that you enjoy you do it more. And, as I think several people mentioned here, consider a small vibrator (or a big one if you are feeling courageous) as an option. You don't just have to use it alone either, you can have your husband use it on you as just another way to add spice to your sex life.

There are many, many non intimidating options to choose from and most everything here has a review (or 20) to read and learn what kind of experience you can expect.
I'd say an egg vibrator or even a pocket vibrator would be a small, inexpensive place to start.

Good luck!