I recommend learning the prepositions properly. :) Look for proper examples in sentences, and you'll understand it soon enough.

It depends on your context, كمال They can both be correct, depending on what you mean. The best example I have is: "For" means the person who will use it in the end and "To" is the person who receives the recommendation. "I have been recommending a particular book TO my friends FOR their children. I highly recommend this book FOR children of that age. --- you can also "recommend someone FOR a position/job." In that case, FOR relates to the final objective or position rather than a person. Hope that was helpful :)

I think better would be OF :))))