registered vs non-registered mail

[yoongie]

Hi, newbie here. I've tried searching for an answer to this but the only relevant topic was posted years ago, so... do most of you opt for registered or non-registered mail? I sent out my first two attempts via registered mail (tracking) about a month ago because as a first timer, I really wanted to know that my letters are being received by someone. However, I've not heard from either and now I'm getting paranoid that it has anything to do with it. Should I send again with non-registered, maybe a couple of months later?