Disclaimer: I am not a professional career counselor.  The advice below is based on my years of experience in industry.

Start preparing now for that summer internship...

Being very well rounded, many MCIT students succeed in getting summer internships at the end of their first year.  Such short-term jobs provide real-world experience and sometimes lead to long-term employment.

Make early use of Penn's career office...

Penn has an excellent Career Services office (McNeil, basement Suite 20, 3718 Locust Walk) which can help with getting your first "computer science" resume ready, and then can help you get interviews.  Representative Rosette Pyne is devoted to engineering recruiting, and she comes highly recommended by students.  I suggest that you begin your resume early in the fall, to be ready for the spate of spring interviews which will be available as early as the beginning of spring semester.

Consider my "special" resume format for computer science consulting jobs...

I like a slightly different format for resumes than the one recommended by Career Services.  See my online resume for an example.  The thing to remember is, that prospective employers will only spend 15 seconds looking at your resume before deciding whether to drop it in the garbage can;  the essential information (skills and education) need to be summarized at the top.  Please don't bother with an objectives statement--in my opinion, it's a waste of space.

Tweak your resume for each job interview...

It is advisable to tailor your resume for the job being sought.  If the job wants C# programming, for example, place that first in the skills list if possible.  My online resume example is for a C# programming job; I have different versions for other kinds of work.  This one was for a parttime summer job at Siemens.

Use the magic keywords in your skills list (the first section of your resume)...

In your skills list, have the first section say "Very experienced in <list of technologies or languages>", or if you're new to the field, possibly just "Experienced in <list>".  The second sentence may being with "Have also worked with <list>."  This gives the reader a very quick assessment of technologies you already know.  Feel free to consider your programming projects for classes as "experience" if you are just starting out.

Ask friends and faculty to critique your resume (you won't regret it)...

Besides advice from Career Services, I recommend that you give your draft resume to one or two experienced people (such as me, or other faculty, or friends who work) for review.  This can help sharpen the first impression which the resume gives.

Use your network...

Everyone you meet at Penn is a legitimate part of your personal network.  It's usually OK to tell them you are a job-seeker; they might just have a lead for you.  Short of being a pest, of course...  If you are doing very well in one of your classes, tell your professor you are looking for work--he or she might hear of something through their own "grapevine".

Did you have a nightmare of a job interview?

We've all had one or more of those.  Discuss it with friends, learn from it, but mend your ego and go bravely on.  A bad interview (or two) is frankly, well, normal in this field--and you probably don't want to work for someone like that anyway.  On the other hand, if all your interviews are going badly, perhaps you need to spruce up your interviewing technique--seek help from a Career Services counselor!

If you are not a native speaker of the language for the interview...

If you are seeking a job in a language or dialect that is not your native one, normalizing your pronunciation of common words and phrases can make a difference.   If you feel you could benefit from such coaching, ask a Career Services counselor for help in finding it.  Or get a friend who is a native speaker to coach you.

Steel yourself to be tested in interviews...

Here are software engineer interview notes on a site created by Penn CIS alum Gayle Laakmann.  Companies covered include Goldman Sachs, Amazon, Apple and Microsoft. 

And, duh!

It is essential that the phone number and your address be correct.  I have known people to lose interviews over such little matters.

No job after all this?

It happens to the best.  Even if you have to take a non-computer job during part of the summer, your technical mind is now clear for some recreational programming--a rare chance to learn things you care about.  The good thing about not being employed for awhile is, you have a chance to study and program at will.  Don't waste it!

Good luck!