Perhaps the right question you should be asking yourself is why you need the higher limit.
If you pay your credit card off in full every month, and you need a higher limit just to give you the extra flexibility and cash flow, then that seems sensible.
If you want a bigger limit just for the sense of security of being able to draw that much credit, but don't have plans to use it, that also seems like a legitimate rationale, however many credit cards seem to increase your limit automatically over time (presuming you've got good credit, etc.) so it may not be worth worrying about too much.
If you need additional credit limit to help pay for a one-time purchase or are simply wanting to improve your credit rating, you should really explore other debt options such as a line of credit at your bank, or a personal loan. Particularly these days you can get a much better interest rate than you can with credit cards.
It's ironic but true that to get a higher credit rating you need to incur debt. At least, in the US. What I've been told by loan specialists is that showing responsible credit card use is okay but the best kind of debt for maximizing your credit rating is not credit cards but rather fixed loans like a car, house, college, or etc. that will have a specific monthly payment. Credit agencies apparently like to see evidence that you can use debt responsibly and demonstrate making payments reliably over a period of time. So, like join a local credit union and tell the teller you want to take out a small loan for purposes of building your credit rating, and buy a new computer, stereo, or whatever. Then make regular payments on that over a few years. Not only will this look better than credit card debt, it'll also be at a lower rate.
If you've accumulated a large amount of credit card debt, and are wanting the higher limit in order to accumulate additional debt, that may be a red flag that your finances are out of balance. It is seductively easy to rack up an enormous debt, but it can be extraordinarily laborious to get it paid off. Two of my family members fell into this trap (one while in college, the other while between jobs). At typical credit card interest rates of 15%, 20%, and even 25%, if carrying debt month to month the debt is going to grow very quickly. If you're in this case I'd say count your blessings for having a low credit limit and get some help getting the debt in control.
Finally, to actually answer your question, yes it's been my experience most credit card companies are quite happy to increase your credit rate. Often you can call their customer service phone number and get it raised instantly. And I think they'd send you a free noose as well. ;-)
