When it comes to source evaluation, do not under-estimate the power of COP.
By this I mean Content, Origin, Purpose. I will go through each one.
Content: They are pretty self-explanatory as to what they mean but what should you write. Well content is an important one, it is you explaining the information in the given picture/extract/speech etc. What you DO NOT want to do is just provide a narrative of what is happening in the source. That will not get you many marks, any one can see the information. what will get you marks is being able to distinguish the importance of the imformation in relation to the contemporary issues of when the source is made.
Origin: A nice lead on to this section. Origin is all the information of where, when and who created the source. This can be vital to getting into the top band of marks for a question. A top candidate would be able to pick up on all of that information and analyse it in terms of its historiography and why those facts are important.
Purpose: Finally, you look at why was this source created? This is where you tie it all together to really look at the basis of the source, why has the Origin created the Content, what do they gain/lose from it.
I will provide a brief example to illustrate this.
"Germany is great" Adolf Hitler, 1931 (Not really but you get it)
So the content is a patriotic gesture to Germany. Not just a good country but a great country. Real passion.
The origin is Adolf Hitler in 1931, this is a bad time for Germany as the economy is falling and hyper-inflation is serious. Would be sceptical as the origin is a very patriotic politician who at this time in 1931 has not gained power.
Purpose of the source? Created for political gain, has not gained power yet so this solidifies his hold on the German people.
These simple tips can be exacerbated to a much larger question, as long as you are smart with your words in order not to waste them, you cannot fail.