Before laying your feelings bare, you should always consider the shortcomings as well as the upper side of everything. Your feelings matter and it is important that you let the other person know of your intentions. The timing for this has to be right and you should do it at the most appropriate time and place, if possible.
First, you have to have a second thought about how well you know the person you think it is ripe to tell them that you love them. You should make sure that you know them very well and have more than just average information about them. For instance, you should know their family and the people that may be close to them or the people that relate to them. You should also know them in person. All the important details have to be available before you tell them you love them. Otherwise, you may be venturing into a very dark cave.
You should also know why it is worth it to make your feelings known. In most cases, you could be dying to prove the feelings and forget the important aspects of your personality and being. You should always consider the downside as well as the upper side of everything before trying out anything.
Besides that, saying 'i love you' will take away from your true emotions and feelings. The other person may perceive you to be very desperate especially if you do tell them prematurely. It will make them question your true intentions.
Moreover, laying bare your feelings could be perceived as a sign of displaying your own insecurities. It could be possible that you are just saying that to make sure that they do not leave. It is like putting them in some kind of prison. If they perceive it that way then, you are as good as doomed.
Laying bare your feelings will also show that you are only being obsessive and not in any way true to what you stand for.