Should I get a credit card to improve already good credit?
I'm a 30 year old engineer, and I have very good credit (mid to high 700s depending on which score you look at). I'm looking to buy my first home in the next couple of years and I want to optimize my credit in preparation for applying for a mortgage. My thought is to get a credit card with a high limit, but obviously never even come close to the limit (to keep my utilization low) and always pay it off before interest accrues. This would give me a total of 5 accounts in good standing (it's my understanding that more is better) and add diversity to my credit mix (my current 4 accounts are all student loans that have never had a late payment). The downsides would be a hard pull on my credit (zero at the moment) and a new account would hurt my average account age of almost 12 years (dropping it to about 9). Is it worth getting another card, or should i just ride this score until I apply for a mortgage in a couple years?
Having spent 6.5 years working for a large regional bank (2 of those years as an Assistant Branch Manager), I can confidently tell you that a credit score in the mid to high 700s will land you in the great to excellent tier. I recall 740-779 being the cutoff for great and 780+ being the cutoff for an excellent credit score. Most of the time the difference between great and excellent was negligible in terms of interest rate, so I wouldn't sweat it too much. Really anything at the great or better level meant the borrower was typically getting the best rate offered. An excellent score allowed for more leeway in terms of loan-to-value ratios and enhancing the terms of the loan. The best thing you can do for your credit is to continue paying your bills on time. Having a high credit potential (credit card limit) to balance (carrying a $0 balance) ratio is also very heavily weighted. More so than the average account age. Therefore, I would consider applying for the credit card and paying the balance off every month. The hard pull on your credit is only a temporary hit, while the benefits of increasing your credit potential will help to raise your score in the long-run.
If you currently have zero credit cards then having one is a good idea, but don't expect having one to improve your credit rating. Just be sure to always pay your credit card bills and all other bills--especially your student loans--on time and your credit rating will gradually improve by itself especially when your student loans are paid off. Be sure not to refinance any of your student loans since doing so suggests that you are having trouble making the payments.
Be cautious about buying a house in the near future; wait until housing prices are much lower than they are today and everyone is telling you why they'll go lower.
The short and simple answer is to not overthink this. You have excellent credit right now. Don't mess with it. I wouldn't add another card. I wouldn't even apply. It wouldn't help your credit much, if even at all.
Congrats on the great credit and good luck with the house!
With a credit score in the mid to high 700s, it strikes me that you are already in good shape. Since your accounts are all student loans and you are on time with your payments, that's certainly helpful. If you add a credit card, the issuer will determine the credit limit. Even so, applying for additional credit is often viewed as increasing the risk that you will need to borrow more. That may well lower your credit score temporarily. But if you plan to apply for a mortgage in a couple of years, it's likely that the score will rise as time passes as long as you are timely in your payments and use the new card lightly.