There are multiple things you need to adjust -- let's step through them one by one:
Unfortunately not on all devices / Android versions, but some camera apps let the user configure where to store the photos (phone memory or sd). Check if your camera app supports this. If so, set it to sd (or "external" -- all but phone ;). If not, you might want to check the playstore for alternative camera apps offering this feature. Videos, photos, and music files are most likely the largest files on your device -- so keeping those away from your precious internal storage will reduce the possibility / frequency dropping into this problem.
As you said you get the "Memory low" or "Insufficient storage" errors, free space on your internal device memory (phone memory) most likely dropped below 25 MB. So as advised by that popup, you should make room. I'm not going into details on this, as this is already explained here multiple times. Check e.g. the following questions:
Additionally, check out the list of most frequent questions tagged "internal-storage", which will list you even more useful questions (with answers, of course).
Once you've sorted out above two things, this problem has solved magically as a side-effect :)