Not all reviews are created equal.
There are many types of review with different intentions and requiring very different amounts of input.
Organisations such as The Cochrane Library or The Joanna Briggs Institute have very detailed specifications on how a systematic review should be done (see Systematic Reviews - Resources tab). Systematic reviews involve a high degree of rigour and significant resources. They are best approached as a team project.
Consider whether you will be able to meet these requirements.
See the types of review tab for more information.