You're going to apply to a school in the U.S. You're reading the rules for applying on the school's website. There's a sentence on the page which says:
Please note that all applications must be accompanied by two letters of recommendation.
You're at a wine store and looking for a good wine to serve to houseguests. You don't know much about buying wine, so you ask a store employee for a recommendation:
Do you have any recommendations for a nice, balanced red?
adjective, recommendation, store, suggestions, travel, wine 
You're talking with a friend about a book that you read recently. You really liked it, and you think your friend should read it to. You say:
I highly recommend it.
To suggest that a person should do something, say "I recommend ___". For example:
I recommend the cheese fries. They're amazing!
I recommend hiring a lawyer early on in the process, to make sure that you don't miss anything important.
As you can see, you can either say "I recommend (noun)" or "I recommend (doing something)".
When you use this phrase, it just sounds like a simple suggestion. It doesn't sound especially bossy, polite, helpful, or rude.
It's common to include an adverb before "recommend". The most common ones are:
Doctors generally recommend keeping the sprain elevated, applying ice packs, and wrapping the area up tightly.
adverb, book, reading, recommendation 
You're talking to your friend about a book that you recently read. It was a really good book, so you stayed awake late at night reading it every night. You tell your friend:
I couldn't put it down.
book, interesting, reading, recommendation, simple past 
Your friend is visiting from out of town. You're getting ready to go out to eat together, and you're deciding where to go. Your friend asked if you knew of a good hamburger restaurant. But you don't eat hamburgers often, so you don't really know of anywhere good. You say:
You know, nothing really comes to mind.
disappointment, friend, recommendation You're writing a letter of recommendation for a former employee who is applying for a new job. You have finished writing most of the letter, and now you're concluding it. You write:
If you have any questions regarding Adele or her performance, please feel free to contact me.
You're shopping for a laptop computer at a store. The salesperson has shown you two computers within your price range. You want to know which one he thinks is better. You say:
Which would you recommend?
recommendation, sales, shopping, store, suggestion 