Give a noun a useful description
Participles can work as adjectives: a smiling child, a damaged box, a written invitation. A description can also follow the noun, as in 'the guests waiting outside' or 'the invitation written by Noor'. Keep the description close to the noun it belongs to.
Distinguish a feeling from its cause
With pairs such as interested/interesting and excited/exciting, the -ed adjective describes the feeling and the -ing adjective describes what causes it. 'I was interested in the talk' describes my response. 'The speaker was interesting' describes the speaker's effect on listeners. People can cause feelings too, so -ing adjectives can describe people.
Use meaning, not only the ending
The feeling/cause pattern applies to those adjective pairs, not to every participle. A broken window has no emotion. A running engine describes an activity; a repaired engine describes the result of a repair. Ask what you want the reader to understand about the noun.
See it in practice
Starting point
I enjoyed the talk, but I described my reaction by saying, 'I was very interesting.'
Using this skill
I was very interested in the talk. The speaker gave an interesting explanation of the photographs displayed behind her.
Interested describes the listener's reaction; interesting describes the explanation's effect. Displayed tells us which photographs the writer means.