Many websites list useful writing tips and hints, but these are the main ones I try to remember:

- Show, don't tell (Don't explain what the character is doing, make them 'do' it)

- Ask yourself: who/what/why/where/how

- Use the five senses: see/hear/feel/smell/taste

- I like to choose the right names for the main characters that sum up everything about them (to me anyway).

Above all, as a dear writer friend once said, 'Writers write'.