Ok this is going to get personal. Very personal. I have written this as sound advice for anyone who may be interested, but primarily females who may be getting to grips with the male member for the first time, or just those looking to broaden their knowledge and skills. Yes, the penis can be daunting for the uninitiated, but I love to share and to help, and so here I am.
One of the main points I can make is that every man is different, we all react to slightly different stimuli, and so what works for one man may not quite work for another. The main penile response is a little more subtle and complex than first appears. In this porn is both a blessing a curse. The classic scenario we have probably all seen of the female pornstar vigorously rubbing the shaft up and down may look good, but in my experience it is of limited value. I will say outright that most if not all of my previous female lovers have had initially poor handwork skills until I showed them how to do it. Unfortunately rubbing too hard, too vigorously and too fast is counter-productive and may be painful to your male partner unless you approach things a little more carefully.
As I said, porn is fortunately a blessing a well as there is plenty of amateur male masturbation material out there. Simply watch how men like to pleasure themselves, and compare several sources from either internet porn or other anecdotal sources so that you have a good idea of what you are doing and can feel much more confident about your manual skills. I am writing this because I want to help you as reader and help you enjoy your erotic life still more!
Communication is key of course, you and your man should be as relaxed, unhurried and emotionally intimate as you possibly can be. In fact, don't start your lovemaking or handwork session until you are both in that place, it's really important. Don't hurry, as this can be really counter-productive. The response of your male partner may vary hugely according to how relaxed he is, the immediate physical circumstances such as room temperature, and his age, degree of physical fitness and virility. However, we men are good at giving out non-verbal signals when becoming aroused, all you have to do is to latch on to and respond to them. If something doesn't quite work, then try subtle variations as you are probably closer to the mark than you think. Smiles.
So on to the main course, I will now tell you about some sure fire male masturbation techniques which in my experience as a man will always work. Use lube where you can, but pre-cum can also be effective once you are beyond first base. Warm, soft hands are very helpful, and you should ensure that your fingernails are in good state too. Long, well-manicured nails can be very effective for a specific grazing stimulation, though they should never be too sharp. Those long, well-manicured and elegant nails are also a fetish which appeals to a lot of men.
Your first job will to make your man hard, and this is best done by varying light and heavier caresses using a combination of thumb and second and third finger pressure points. Caress, stroke, glide your thumb and fingertips across the shaft in multiple directions. Experiment, and see what works for him. Resist the temptation to take the shaft between thumb and forefinger in order to stroke the whole shaft too quickly, and let your man's erection grow naturally. The combination of lube and those soft warm hands should do the trick. This is really where you can experiment and give your man a lot of pleasure. This fingertip masturbation is all about the degree and angle and speed of pressure that you apply.
As you progress, that fingertip pressure should become more continuous, more firm. Through your fingertips you will feel the vibrational sensations you are creating in his shaft. The longer the continuous sensation, the more pleasurable it will be for him. I personally am very responsive to a slow firm circular movement using the thumb and the second and third forefingers on that pressure point just below the head. For those not in the know, this is always the most sensitive area of the cock, and where you can give considerable pleasure as that pressure stimulation will be travelling right up and down his shaft and he will absolutely love it. There are other areas of the shaft where this technique also work, and a side to side caressing motion across the underside of the shaft can be very good also, but this is the one where you will masturbate your man the most efficiently. You can do something similar on the glans or head of the cock, but do bear in mind that your lover's skin is particularly sensitive there.
If giving manual stimulation to the glans then definitely use the lube and soft hands technique, as you can cause some discomfort if you are clumsy. Forming a cap using the palm of your hand over the head of the cock is highly pleasurable, especially if you use a slow corkscrew stimulation movement. Given its sensitivity, the head of the penis is also extremely susceptible to oral stimulation, but that is a whole different topic of conversation.
Do check in with your partner very regularly, ask him how things are going, and check with him if you are doing ok or need to make any adjustments, especially if you are learning your craft. You can mix things up too, revert to mouth on mouth or whole body kissing if you feel the need. Only when you feel that your man is quite hard should you take things on to the next stage. This would be an ideal opportunity to slip on a cock ring or condom and to move on to vaginal intercourse, but if you want to continue down the hand work route then you will probably need to change position.