Ok, to start off, what plane are you useing. If it blows up every time you attempt to land, then back off the throdle.
To start, you are going to want to give yourself a LOT, and by a lot, I mean like as in you can bairly see it on max settings. Then, the fun begins.
You will probaly want to get a altitude mod, so you can see how far you are to your impending doom. Press on the S key, or your back key, to start to decelrate the vehicle. If it has emmiters that click on after a certain speed, use those as measures. Gradgulaly throttle down, only useing your forward key if you begin to free fall. In blockland, its prity much impossable to do a RL landing, so you are best doing a "land-on-a-1-stud-landing" which entitles your wheeles not hitting the ground untill you are at a full stop. This can be more challenging, but give it a try before you try to continue with RL landings.
I hope this helped.