You can't. A pretentious person is so full of himself that he will not listen, and if he does listen he will not understand.
If the person is paid for the advice, she/he is a counselor or personal coach. If the person gives unsolicited advice and is not paid, she/he is called a nuisance.
A person who gives unwanted advice is usually called a kibitzer.
Other than on the internet, a young person can get advice on tongue kissing from friends, relatives and magazines. But the best advice a young person can receive is from their parents.
A person whom you respect and who offers you advice and assistance is known as a mentor.
Advice given with wisdom to back it, usually from an older person.
There isn't any good sites that gives good advice. The best advice is to get the information in person from a good person that you know and trust. You can go into a chat room or Facebook but they aren't good sites for advice.
The plural form for 'piece of advice' is pieces of advice.
A person who offers advice without being asked is someone who cares enough for you to offer that advice and you have the chance to think it over and take it or leave it.
There are several websites that a person can go to get advice on dining in Philadelphia. These websites include VisitPhilly, DiningIn, and PhiladelphiaRestaurants.
A person giving advice is often referred to as an advisor or counsel. In specific contexts, they might also be called a mentor, consultant, or coach, depending on the nature of the advice and the relationship with the recipient.
One can find advice on how to become a morning person at the website "refinery29". The website offers a slideshow of 6 photos revealing how to become a morning person.
A person can get advice on how to sell a house from a real estate agent. These individuals are very knowledgable about the selling of homes and should be able to help you.