Need Ideas and tips about modelling

It’s not been much time, I’m using blender, so still I can’t model many things such as simple structures…like i want to model an object like shark’s fin but the broader side will be thicker… But wondering how to and where to start.
I’m not getting a clear idea about how to start those modelling, not just the fin but anything… how to start ?

I googled “blender shark tutorial” and the top link was this:

My advice to you is to watch tutorials, model something every day, and if you don’t give up you will look back at this question someday and smile.

Some great tutorials for beginners on blendercookie and youtube. You should look there and follow along. Pause it when you need to even if its every 30 seconds. Also if you can find a tutorial that shows the key commands thats very helpful as well. I used this one to get started but their are more basic ones then that to get you started. One big thing that helped me out is that when your modeling in 3D and your just starting its important to move in only one of the X, Y and Z axes ay any given time. What makes this really easy is using the Numlock views that are 90º or using the gimble tool. This way you can be certain your not moving in the other planes. As primarily a 2D artist it took me a while to get used to thinking this way and it can still trip me up, but its really rewarding stuff and well worth learning. Hopefully this is some help to you.

Oh one other thing. If its your first project you might try a project that you have sketched out from the front and side view like the guy did in the tutorial I posted before. This will let you focus on the mechanics and learning the UI rather then being creative with the modeling. You probably want the ability to model without a diagram eventually but I think its a good rule of thumb to always have references of what your modeling or at least something close. Good luck to you!