In the name of Allah the Most Beneficent and Merciful
There are many different recommended methods of finding a suitable partner for marriage which are allowed under Shariah law.
1. The first and most common is for the parents of the individuals to find a suitable partner via their connections within the Islamic community. Here it is important that you have a good relationship with them and you have a say in what type of partner you are looking for and you have final approval.
2. Another method is to use influential people within the community to find a partner for you, such as the Imam or a female scholar who has contact with other people looking for a suitable partner.
3. A person may also use their friend circle to pass across the message that their friend is looking for a partner. Please always make sure that the friend is trustworthy and knows what you are looking for. Also all contact is made with a Wali (guardian present) and not alone. For a female they may ask their married friends if their husband knows of any suitors or vice versa for men.
4. It is also fine to meet someone through college, university, work or a community gathering as long as the parameters of modest behaviour are observed. If you meet someone you would like to discuss marriage with, in case of a sister then just arrange for the brother to meet your Wali or family. So if you know someone you want to marry then speak to your parents/ family and get them to speak to the boy/girl's parent/family and get the ball rolling.
6. It is also permissible to find a suitor via recommended and responsible matrimonial agencies and websites. I can’t vouch for all of them so one has to be careful. However, on these one should ensure that the contact details of their Wali (especially for the sisters) as it is for their protection is given. Then all contact is done via them. Under no circumstance should a sister post her photo on the website as not only is this dangerous but also Haram.
A note of caution about on-line matrimonials: The nature of cyberspace lends itself to anonymity. It's very easy for people to misrepresent themselves on-line. Trust your instincts. If you feel that something's not right with someone, then don't pursue discussions with them. Never give out your personal information.
Once you feel that someone has potential, get that person in touch with your Wali or family. Make sure that your Wali or family thoroughly checks this person out before you proceed with the first meeting and then at that meeting it is not permissible to meet alone but the sister should have a Wali present. And always insist that the potential suitor provide references. This advice applies to whoever you meet, whether it's through a website or at college, uni, work or anything else.
If the right method is chosen and the Shariah is upheld Insha Allah one will find help through Allah to find the chosen partner. This is the alternative to getting involved in a boy/girlfriend relationship which is not only Haraam but dangerous.
Of course Allah knows best