So you've decided that you are interested in pursuing an internship or research position, now what? Luckily there are a slew of resources out there with you in mind!
The first step is to prepare your application materials. At the very least an updated résumé will be required, possibly with a cover letter attached. If you need help developing your résumé visit the career center, they are here to help you with all aspects of finding a job.
Secondly you'll want to prepare yourself by finding out what will be required. Get ready for an interview; know what you want to do and why so that you're able to communicate it with confidence and lucidity.
Next you'll need to identify who it is you'd like to work for. When you have some leads start looking into them a bit more deeply. Find out what the company does, or the main research projects being conducted by a professor, and look into them more deeply. You don't have to know everything, but you should be able to hold a conversation on the subject. It will make you a much more appealing candidate, demonstrating that you won't need them to hold your hand from start to finish.
There are a number of companies working in cooperation with the LIAEC, and many more who aren't. Ask your professors and find companies that have ties to your department. Make yourself known by attending society meetings, shake hands, take business cards. Most importantly, don't give up! There are many students who send an unsolicited résumé by email and get no response, and simply think that door is closed. It isn't! Make phone calls or appear in person, put a face to your name and get a definitive no before moving on. More likely than not your résumé is just another in a stack. Move it to the top by demonstrating some commitment and giving them a reason to hire you.
If you're interested in research start by asking your professors about the research they're doing. Make a good impression, use the internet, research research! The sheer volume of research being done at Stony Brook means that there is almost certainly a position for you somewhere, and if you aren't getting any leads try Brookhaven National Lab. If you can demonstrate competence and professionalism in the classroom and your personal interactions with your professors, more likely than not all it will take is a few questions to find yourself a lab position. Most importantly, don't give up! Your professors likely receive dozens (if not hundreds!) of emails a day. Yours might be overlooked or placed on the back burner. Find out when their office hours are and show up! Ask questions, find out what your options are, make a good impression and make sure they know your name.