If you wish to gain working or professional level proficiency, you must not miss any opportunity that helps you advance your language skills. Do not be afraid of making mistakes. Mistakes are part of your language developmental process. However, you must pay attention to your mistakes, especially the recurring ones. Work on your errors before they fossilize.
Some errors are more costly in terms of meaning than others.
The ultimate goal should be to eradicate all major and minor errors irrespective of their functional load. Productive skills are more demanding because you, the learner, has to know the correct pronunciation or spellings, endings, word meanings, structures, and the rules of usage. Remember, receptive skills function as a rich source of linguistic and cultural input, and in turn help in enriching the output. Identify your learning style and use appropriate strategies for advancing your language skills. For locking new words into the memory one may use visualization, sound, use of motor activities, or any combination of these.