An artist who lived in California wanted to learn how to paint polar bears.In addition his painting skills were quite modest.I suggested he do many small experimental studies by looking at photographs.It didn't matter if they're finished or not for they were ways to learn about bears.After 250 studies his first painting without a polar bear or a photograph.He was totally surprised at how well his polar bear turned out.Also the standard of the work was infinitely better than it had been in the past.He had internalized his learning.The polar bears he created were not a photographer's either as they were his!As a way to learn about realism use photographs (at least to start with).Any photograph is of something.If you want to learn to paint portraits, then choose facial photographs.So like the Californian artist don't just select any focus on one.Then even from the start you can become a specialist.You get to understand portraits.Over time you will develop the individual paining skills needed.You will also know how to paint your subject your way.Eventually you can focus on another subject.If it is related to your original theme you will learn much quicker.Focus on one sex then later the other is an example of portrait focus.You'll note the similarities and also the differences.You could go from portraits to head and shoulders studies and then full figures.Follow this pattern for long enough, and you'll be able to paint anyone!People who do anything well also do it faster than those who don't.That applies to painting as much as anything else, it's an indicator of skill.Skill in art, sport or even medicine is basically the same phenomenon.It's practiced behaviour in action.Most artists don't do anywhere near enough paintings to develop any real skill.Many small experiments will beat one or two major efforts every time.But you must do the 'hard yards'!Painting a large number of experiments develops painting skill, and attitude.You'll become more discerning, because you acquire more experience.You'll not need, nor want, other people's assessments.A number of experiments at the same time increases productivity.For you reduce wasted time.If you run into a dead-end with one painting move to another for a fresh start.When the initial painting is returned to, there will be a different attitude.Otherwise set it aside again.Working on a number of paintings at the same time also saves materials.A particular colour can be applied to the work for which it was intended.BUT there are bound to be other works where that same colour is appropriate.When you buy paint, buy in quantity, but only use as needed.Can't remember what you did before then do whatever you think of now.In the end it doesn't matter!Usually you'll find most works will finish fresh and roughly about the same time.Avoid major works.They take time (years), usually done slowly and are often large and complex.You'll tend to labour over them as you seek to do your best.You learn to paint by painting.You do not learn by someone telling you what to do.That way you learn they know what to do and if you get stuck you ask them.But you can also learn by looking.That's how you learn about the appearance of things.Traditional art learning is based on looking and putting.It's possible to learn many simple things and gradually combine them.A problem is that you can only paint what you can see.But by actually painting such things you get to understand their appearance.You also develop skill at depicting those you do most.Let your experiments evolve.Those that don't work out won't matter as you learn a great deal from 'failures'.You'll learn what to do and what not to do next time.Regard these as exercises or studies or experiments.They are never going to be framed, sold or kept for posterity.Just do many and do them reasonably quickly.