It's ok, we all start out weak at something and yours is a very easy problem

First of all, when you wake up, you might not remember any images, but you probably will feel in a certain way. You might feel kinda jumpy, maybe happy or maybe even sad. Elaborate, think about the feeling. Why do you feel that way? Once you manage to connect the feeling to anything, be it a face, a certain situation or perhaps another feeling, you're already started. You just have to start linking everything and you sometimes end up with a whole dream just out of a certain mood you woke up with.

Maybe you don't wake up with a feeling, or an image, but maybe there was a sound, a face, a place, it could be anything. Just try to connect it to whatever came first or try to place it in a certain environment. If it's nothing but a faint detail, right it down anyway! If you read it again later it might make you suddenly remember everything, trust me, it has happened.

If you happen to wake up and you remember absolutely nothing, try thinking about people you know, things you like, things you did yesterday, thoughts that constantly come to your mind and if you happen to remember, the last thing you were thinking before you went to sleep. Surely one of these things will bring back a dream scene or two. I always do this in the shower after I wake up. I start thinking: "my brother... no... school... no... my girlfriend... yes!" and there I have a person, I think a little more and I can place her in a dream scene, I think about the scene and what happened before or afterwards and I have a complete dream.

Right everything down! Even meaningless details can be of good use and even if you can't connect them to a dream, they still give you an idea about what you usually dream.

Don't give up hope! If you do these things I assure you, you'll end up having an awesome recall