If you're in a house, what is happening in the next room? If there are other people around, what is your relationship with them? Are they older or younger than you? Do you know them well?
I have a memory that I used to assume occured when I was a child, except it never 'fit' this life. For one thing, I am talking eye-to-eye with a man (hard to do for a child) and am also standing in an area vastly different than any place I'd been before. I can also smell the marshiness of a large body of water nearby.

Recently I read a biography of Robert Baden-Powell and afterwards dreamt I was following him through tall African grasses under a blue sky. Other than this, I couldn't tell you much about what was going on around me with too much detail. Compared to the memory with the large body of water explained above, the dream was very flat and didn't have the texture of a real memory. Of course, I never thought this was a memory, but it gives you an idea of how a person could get confused if they're just starting out.

Verifications and Research
Someone told me the other day that all memories should be considered false until validated. I don't necessarily agree since some memories are so bland that there is nothing involved you could necessarily validate. A memory where you're running through an empty field could of happened last year or 200 years ago, since there is nothing present (like farm machinery) around to give you any info.
HOWEVER, I am big on doing your homework and getting those historical validations whenever possible. I have found that the experience of knowing about a past life is 25% memories/feelings and 75% research. In a society that craves and expects instant gratification (we want our internet fast and our pizza delivery even faster!), the idea of researching a tidbit of a memory for 5, 10, or even 20 years doesn't seem very fun. Validation and research takes commitment and TIME. You must be willing to put in both and expect disappointments along the way.

Look at your memories for something obscure you can validate. This element should be something that is detailed , not well known, and that you have to dig a little to verify. Someone I know who was in the SS in their last life remembers the gas vans being used during the Holocaust. That alone isn't very obscure, but this person could also describe in great detail the vans, how they were used, the emblem on the front of the trucks, etc. without prior knowledge of any of this.
Also, don't expect bucketloads of memories to fall out of your brain. Even the best cases aren't necessarily loaded with dozens of detailed memories. If you find yourself writing about your past life and it reads like a flowery historical novel, something is not right.

Blurriness
Real memories also don't typically become cloudy with time. If anything they should become more clear as you focus on them. At this point, you may just find that little odd detail you can research. With that being said, I recommend that you write down a potential memory and it's details as quickly as you can when you had them, because if it came in a flash or dream, you actually may forget the little odd details that could be your golden ticket to validation. 

The Trap of Obvious Stuff
I don't believe it's a given that people remember large, historical events. Even the most accurate, most researched, accepted-as-truth cases aren't full of memories that could be found in Encyclopedia Brittanica and are usually just regular life stuff.

Does this mean I consider memories of commonly known nature junk? No, because I also believe it's true that there are triggers for these well-known events all over the place. You can't turn on the TV or visit the bookshop without WWII or the Holocaust subjects blaring out at you at every corner. If lived in those times, it'd be pretty hard to ignore! I also think that traumatic historical events could surface more prominently simply because of their harshness. I recommend, though, that you treat such a memory with added scrutiny and keep your skepticism within easy reach. You need to validate everything you can to be sure it isn't just your imagination running away with you.

And...
Above all? You need to trust your gut. If you feel that a potential memory has that certain quality of reality and you just can't get it out of your head, then there is probably something there. I personally have gone to the mat over something Nazi Germany-related that I KNOW to be true. My only 'validation' is that someone else also remembers it. Not too much proof there.
I like to think that the historians just haven't caught up with me yet!