When it comes to online security you should check each and every detail on it.
I never submit my critical data on any site. The site has to first build the trust in me. When it comes I just registering then dont give away your primary account so easily. It depedns from site to site. I have registered on mouthshut from my primary account as I had faith in this site as one of my best friend invited me to this site.
First tip is that avoid giving away your primary email address.
Secondly keep your password strong meaning use alphanumeric passwords and use caps lock if possible.
Avoid leaving your account logged in.
Whenever you send your sensitive data check if the site has ssl certificate meaning it should have https before the main URL.
If your logging in from someone else’s computer then check if key logger is installed in computer.
Keep passwords that are difficult to guess.
Never click on any suspicious links. Even if you click on the link make sure you don’t enter any details. Its advisable not to click on suspicious links.
Never share your passwords or click on remember password while logging in for the first site.