Depends on the person and the instructor. Some people are better and/or more interested in certain subjects than others. So some subjects will be harder and some will be easier depending. Some instructors have terrible English and/or are just bad teachers. And it's difficult to learn anything from them.
Try to do internships when you can. It's good to have some actual experience. Not just because it looks good on a resume. But you have personal experience of what it's like to be an engineer, so you can be more motivated(or less if you didn't like your internship) to hang in there when classes get tough sometimes.
And the three hardest things about being an engineer, deadlines, deadlines and deadlines. Get used to them when you're a student.
I would say one based on knowledge, that is math. Engineering is math, but unlike a math degree where math is the end, the math in engineering is only the means to the end. Your math fundamentals like trig and algebra need to be so well practiced you don't waste time with this stuff because the time lost in tests will kill you. Trying to recall what Euler identity from trig applies in a certain case shouldn't be the killer in an AC circuits test or homework question. Which Laplace transform to use when getting a frequency domain expression into time domain shouldn't be the time killer in a test. Your math needs to be practiced and solid or it will be a major hurdle in all subsequent work.
The other "hardest part" is a social one. You are an engineering student. You're basically getting a something a little short of a math degree on the way to getting another degree that relies on math. You will not be out partying, you will not tolerate noisy roommates or other distractions. You will be studying hard the whole time unless you're the mystical whiz kid that sticks a book under your pillow and learns by osmosis. You cannot let the distractions of the outside world get to you. Your friends must accept that your social life isn't going to be like a lib arts History major if you want to have any chance of academic success in your field.
Unless you are a genius, the commitment of time and effort to achieve your goals. Engineering students are normally some of the hardest working students at school. They are competing with the math majors, chemistry majors, physics majors and other engineering students in each of the different engineering disciplines in the lower division to achieve respectable grades to be able to advance to the upper division.
The tests are hardest.
Thinking up a different reason every day for not doing your homework.
Addressing your history professor as "Doctor".
About to begin my studies, just want opinions
