Wing down vs Crab is one of those debates that will go on forever - each has their pros and cons, and in certain a/c and circumstances, you may not have a choice. An experienced pilot should have both in the bag of tricks.
I personally think in a 152, at student level, there's a lot to be said for wing down - the timing is not critical, and there's nothing wrong with landing on one wheel. Establish the wing down really early, and track the centreline; then all you have to think about is the flare/hold off.
As you get more experienced, you will establish later and later. Once you know the plane well enough to know exactly when the wheels are going to touch, the crab and straighten approach can be used effectively, but the timing is critical.. and if you straighten too early, you need to transition to wing down in the hold off anyway.
For the landing; it's been covered here - fly a bit more often, try to relax and feel it (don't fight it), and check you have a consistent seat height when you fly (that affects the picture..)