Take a course in how to do a systematic review/meta-analysis. Doing the systematic review right is the most important part. If your systematic review is poorly done, your meta-analysis cannot be good. The objective of a systematic review is to identify all studies answering a particular research question. Short of that, you want a random sample of all studies answering the question. This includes identifying unpublished studies, studies published in foreign languages, etc.
Take a course in how to do a systematic review/meta-analysis. Doing the systematic review right is the most important part. If your systematic review is poorly done, your meta-analysis cannot be good. The objective of a systematic review is to identify all studies answering a particular research question. Short of that, you want a random sample of all studies answering the question. This includes identifying unpublished studies, studies published in foreign languages, etc.
Sounds like you are new to the process. If that is the case, then you need a good, experienced 'team' around you - including a statistician. It is not a wise idea to conduct a meta-analysis on your own - even if you are an expert. Cross-checking of daya is required etc.