Before we proceed, consider watching this little explanation on synthesizing information:
A common challenge faced by a novice researcher is to produce a synthesised literature review. As opposed to an annotated bibliography - that merely focuses on individual sources which are presented separately from others' work - a synthesised LR is about how you arrange the key findings/information e.g., factor, benefits etcetera in a more meaningful way that supports your research idea. A synthesised LR is not just a summary of what has been done, but also relates to how you use the information from different sources to find a research gap or on other words what has not been addressed. Ultimately you want to convince your readers that the gap is important enough to be studied.
Basically, prior to synthesising the LR, you need to search for literature, for example - articles by researchers who conducted a related research to your research interest. However, producing a synthesised LR is not a straight forward process. After reading all the sources that you have, make sure that you identify the key ideas. Then, try to organise the key ideas or elements by putting them into different themes or sub-topics. If you are familiar with coding in qualitative data, you may find this process to be similar. After you have arranged the key elements into topics or sub-topics, then only you write the whole ideas using your own sentences based on your reading from the literature and start citing the sources according to the themes or topics/sub-topics. Remember that the sources my be repeatedly cited as you write.
Those who had trained themselves to write a synthesised LR would find it to be useful and helpful in elevating their confidence to produce a better quality of LR.
Note: You may want to read my writing on how Nvivo can help us to synthesise our LR HERE