Analyzing your sources before you start writing your paper will make actual process of writing easier, faster, and less frustrating. And it doesn't have to take a lot of time.
Look over all the resources and information you found. Look for weak sources and gaps in information. For example: if you're writing a paper about Arkansas State University and you forget to find out what date we went from a college to a university, you'd have to stop in the middle of writing to go find that information.
It's better to find a problem now than mid-paper. For most of us, we get in a groove when we're writing and it can be very frustrating to have to stop in the middle of a paper. If you're like me, it's way harder to restart a paper and regain your momentum once you have to stop and do something else.
After reading through you sources, do you understand the topic better?
If you don't understand what you're writing about, neither will the reader of your assignment. You may need to evaluate your sources. Were they appropriate? Don't use jargon filled articles written for doctors if you're just working on a two page paper. That's too much. If your sources are appropriate, did you forget to find introductory information before finding the harder stuff? Also, don't forget to make use of tools such as dictionaries and thesauri.
Does the information you've found answer your question and provide evidence?
It's easier to take things out of context and twist things to fit your thesis. However, your professor will know and your grade will reflect it. Plus, you're cheating yourself. Look at your original problem and the information you've found, is it all there? Do you need to go back and find more? It's easier to do this step now than it is to have to go back and do more research in the middle of writing your paper. Also, do the sources provide examples and evidence to support their claims? You may find that you have too many sources on theories and not enough on outcomes. Again, go back and fill in the gap.
Does the source contain enough information?
Don't use a source for just one sentence out of it. The whole source should be relevant to your topic. There should be plenty of other and more relevant sources out there to choose from.
Can you defend all your sources? Are there any your professor may not approve of?
If there's any doubt that your professor won't accept the source, either toss it out or ask their approval before including it. If all has gone well, you should have enough sources that you can weed out the weaker ones. Strong sources make strong papers.
Are your sources current and accurate?
Having historic information is good, but things change fast. Chances are, that 20-year-old article on heart disease is no longer accurate. Find something newer to balance the historical information. Also, pay attention to facts in the source. Do your other sources support it? If you have one source that's completely contradictory to all your others, that may be a red flag.
Are the authors credible and non-biased?
You should always use sources from experts in the field. You don't want photon information from a geologist, you want a physicist. Check the author's credentials. Are they qualified to be speaking on the subject? Most scholarly articles will be written by people with degrees, affiliated with universities and institutions and will have their degree information and background clearly presented. Finally, check for bias. Are they distorting information to support their cause?