Make a suggestion or give advice
We have already seen how the special noun ほう is used to show a choice between two alternatives.
お寿司より、ラーメンの方が好きです。
I like ramen more than sushi.
When used with the -ta form of a verb and いい, it shows that one course of action is better than another, or that doing something is better than not doing it, and can be used to give advice:
毎日運動したほうがいいです。
You should exercise every day.
This structure definitely implies that the listener should do what the speaker thinks, and can come across as quite bossy if not used with care. A way of softening the message is to provide context.
健康的な生活をしたいんだったら、 毎日運動したほうがいいです。
If you want to live more healthily, you should exercise every day.
To make a suggestion, without implying it is better than any other course of action the listener might be thinking of, you could use -たらいいです。
料理の本を買いたいんですが…
I’d like to buy a cookery book (implied: have you got any ideas?)
紀伊國屋へ行ったらいいですよ。
You could go to Kinokuniya.