A few hints;

Making a Friend Request

1) Don't randomly send friend requests.
i.e. do not just go from profile to profile clicking add friend 100 times in a row.

2) Make friend requests to people that are active on the site.
Find members that are making comments on blogs and are actively posting. Otherwise you may find you have a huge number of unanswered requests.

3) Visit the member's website before making a friend request.
Find out something about a person. Do you have common interests? Send a targeted comment in the friend request.


Receiving a Friend Request

1) Never accept any friend request blindly.
Send a message asking them a general question. If they answer, then accept their request. If not, ignore them.

2) Be wary of accepting requests from people who do not have a picture.
People that do not post a picture are more likely to send you spam, and are probably less serious.


Managing Existing Friends

1) Immediately remove any friend that sends you spam.

2) Immediately remove any friend that sends you more that one invite to another site in a week.
If you notice that you are getting 15 invitations to all kinds of social networks, then you have a friend or two that you need to eliminate.

3) Spend a few minutes a day removing friends that are sending you spam and excessive invites.
If you do not, then things will quickly get out of control. 5-10 bad friends can turn your email inbox into a nightmare.