What type of class was this? Just curious.. I took a quick look at your models, it looked like a pretty cool project but you should be careful with underconstraining your sketches. It will come back to bite you eventually, if things are free to move around they eventually will and it will probably happen at the worst time (like you notice it right after the machine shop calls and says "hey this part looks all wacky, are you sure that's what you wanted??") Get in the habit of doing things right everytime, a little time up front saves tons in the back end. I know it might seem faster to just wing it sometimes, but the extra time is worth it. If you can grab a line or part of a sketch and drag it around then you really aren't done sketching yet, I think someone on here called it the etch a sketch technique, its a common practice.
It looks like you are looking for some general tips so I will give you a few that I usually give people that work for me...start your sketches at the origin and dimension your profile to that origin point. If its symmetric then this will save you tons of time later because you can draw a feature and then mirror or pattern it around the origin to quickly duplicate parts. That is a huge time saver, which brings up my next point...never draw the same thing twice! If you can create a feature then pattern it somehow that's the way to do it for sure.
Also keep your sketches simple, that's another big one, it looks like nothing was overly complicated in your model, but that's a good point to keep in mind for future work.
The last thing I will say is that before you start modeling, think for a few minutes about what you need the final outcome to be and what would be the most efficient way of getting there. A little planning goes a long way.
Good luck on your project.
