What kind of sketching is good to just keep from getting rusty? Do you guys sketch something every day? I am a student , so would you just suggest get a sketch book and doing something everyday?

I usually have a small format moleskin sketchbook for jotting ideas with me during the day. You sketch a lot more if you have easy access to a sketchbook, and those little ones are great for doodling out quick thoughts. I just try to draw out thoughts, kind of log them out and see if they can apply to anything else later… usually it is crap, but it is good practice.