Boring as it might be, the first thing you need to consider is your personal safety. One of the biggest strengths of any online dating service is the anonymity that it provides. Unfortunately, however, this strength is also its biggest weakness. You will never completely know who you're interacting with until you've met and spent some real time with them. This can obviously be dangerous unless it's handled with real care and consideration. Several online chat rooms have had to be closed because of this very reason.
However, I do believe that using online dating services can be safe and enjoyable, so long as you follow some simple rules and hold your own safety in the highest regard - above all else. If you have to make sacrifices because of this, then so be it. You will find that dating service members will appreciate you taking an interest in your safety, because it adds to the safety of the online dating service community as a whole.
This is by no means an exhaustive list, but follow these points as a base:
Never under any circumstances give out your personal details.
If another member wants to talk to you by phone, then don't give out your number. Get the number of the person that wants to talk to you instead. Protect yourself.
If you're not a sceptic, now's the time to become one. Question everything you read and hear.
Never meet someone alone. Preferably go as a member of a group of people. If you can't do this, at least arrange the first meeting in a public place like a cafe and let someone you know where you are going.
Make use of organised singles events in your area that are specifically organised by the larger online dating services.
If you are meeting with someone, you'll probably be nervous. Never drink alcohol to calm your nerves. Make sure your powers of judgement remain clearly focused throughout.
Always be wary of bits of information that seem too good to be true.
Never be persuaded to do anything you're not completely comfortable with.
Use good common sense throughout and you shouldn't have any problems. Dating services like Matchfinder really do work very hard to ensure that they provide a safe environment for you to enjoy. You are also likely to be provided with more information on ensuring your safety after you've joined. Be sure to read it all with care. Enjoy online dating! Let's get on with things...