How can I make sure I can/will find the right major?

Do some reverse job interviews. Contact some places with hiring potential which may interest you. Tell them that you are making a life decision, and that you would like someone to talk with you about what the job has to offer an applicant.

Your in luck. Most engineering programs have the same first year. You can find out what you want from the first year.

In conjunction with talking to people in the field, like @Here2_4 mentions, you should also consider getting in contact with instructors in the department and students in the classes. Don’t hesitate to talk to people. Read books about the different areas, leaf through some of the textbooks you might be asked to read.

And also note that it is possible to change your mind, too. While it may be difficult at some institutions, particularly if you’re switching into a more impacted area, but it isn’t unheard of that students change their mind.

Consider what you like doing. Tinkering with software and electronics? Wrenching on cars? Are you interested in Geology, buildings and structures? All of the above? Consider the “big three” Electrical, Civil & Mechanical. I’m an electrical but do things that a computer engineer and civil engineer would do. There can be significant crossover and you can’t really go wrong with any of the big three. You should go around and talk to as many practicing or retired engineers as you can. I’ll go ahead and say that faculty advice at the university should be taken with a grain of salt. Many of them have not actually worked in the field in any practical sense outside of research. If they have then hit them up for advice and a good feel of what they did when they worked. I’m not the only engineer on here, we have several @luckyguy (not sure what type), @hominid is a programmer and I’m sure there are one or two more.

The first year is identical for all engineering programs, the second year is very close to the same so you have about a year and a half to decide without it impacting your schedule. I will say though that the big three will net more numerous and more diverse job opportunities.

Whatever you do, make doubly sure you can get a professional license with the degree program you choose. Some programs will say “engineering” but are actually “technical programs”

I found what @talljasperman wrote correct, the first year or two is packed with general-purpose science and math. Then you will need to start specializing.

On the other hand I dropped out after three years because I was floundering. Promised myself I wouldn’t go back until I knew what I was going to concentrate on – one of the best decisions I’ve ever made. I worked a couple years as bench tech, leveraging digital electronics studies.
At some point I observed that I had spontaneously spent a lot of time, and did very well, on all the programming classes I had taken. I went back to complete a double major Electrical Engineering and Computer Science with a software concentration.

Other people have given some great answers to this question with useful advice for figuring out what major fits your best. I’d like to offer a different perspective, which may or may not be right for you.

I chose to study engineering by flipping a coin, and once I got to engineering school I picked electrical engineering by glancing over the required courses and thinking “these look interesting”. So far I have never regretted that decision. As a similar story, a friend of mine chose economics because “the professor was hot”, and now she has a job as an economist for the NYC mayor’s office.

You don’t know what kind of person you’ll be in 5 years. You know what you like now, but that will totally flip upside down. And who knows what opportunities will come your way. I think there is a limit to how much information you can get about which college major is right for you, because you’re making that decision on behalf of a person who doesn’t exist yet.

I think what’s most important is that you maintain an attitude of curiosity and a desire to explore. Your college might group the engineering disciplines into 5 or so categories, but there are literally 100s of wildly different and unrelated “engineering” jobs in the real world; the basic categories of electrical/mechanical/chemical only scratch the surface. In 10 years you may find yourself to be a world expert in a field known only to 35 people. Don’t be afraid to make uninformed decisions about your course of study. Keep an open mind and it will take you places you never expected.