I think the question I get most often is "where to start"...Personally I work from my own photos which I think is a good idea because you carry the feeling with you. There was a reason you took that picture..probably because it caused an emotion in you. You will probably put that feeling into your painting.
I love to draw so I don't photocopy and trace. I do find it a little dismaying how many artists trace...it is a great way to start but once you feel comfortable you should really try your own impression of the picture. REMEMBER..PAINTINGS ARE NOT PHOTOGRAPHS! you only want an impression of the picture.
The next thing I remind my students is use WATER after all it is watercolour :) Dry brush strokes can be used in landscapes for texture but most florals and still life need loose, wet paint to flow on the paper.
The next important thing USE GOOD PAPER...you can't create a good picture on anything under 140 lb. I love 300 lb. Arches but 140 is adequate. You can tape the paper down with masking tape to a good stiff board of some sort. If you want to get rid of the sizing by dipping it in water for awhile and then staple it down ...fine..but after years and years of painting I don't bother. Sometimes I do wet the paper with a sponge and let it dry then do my drawing.
CHANGE your colour every inch or so...by doing this you get an interesting picture. Using transparent colours will keep you from getting mud. I think 3 or 4 colours in a painting is enough. This way the painting lives together.
Colours directly from the tube are okay but I find mixing my greens you get a nicer green and I never use BLACK...Winsor Red, Winsor Blue and Winsor Green will give you a fabulous black and it will be a black with life!
Don't over use your salt... it is great if your wanting a little action on water or beach...perhaps a little in behind a floral..but too much is just too obvious.
More hints to come later..