The second advice Polonius gives to Leartes is to always stick close to true friends. This is a good advice for someone starting out in the world. I think this can be one of the most important advices someone can give, because true friend will ever stand beside you, no matter what, they will always help you, and they will never be a bad influence to you, so you can find trust and support on them. If you stick to a bad friendship, or cut the bond between you and a very good friend, soon enough you will find yourself standing alone, with nobody there to give you a hand, or to help you.
And the last but not least is that if you always keep true to yourself, you will develop self-confidence and integrity. I think this means that being yourself, and not what everybody expects you to be makes you a better person, an integral person, and you will develop your self-esteem, so you will believe in to the values, beliefs and attitudes that we hold about ourselves, without carrying about what people might think. In conclusion, Polonius is giving useful advices to his son Leartes for the future, for him to appreciate and use in his trip. I think we can all use this advices, in our houses, in our schools, it does not matters we are not in a foreign country, but