Use English. Make it simple.
Avoid long, complex sentences. (Break them up.)
Use 'I' and 'me' if accurate.
People from many subareas of biology read our journal. So keep jargon to the minimum that you absolutely need. And define all terms that might befuddle someone outside your narrow area. (Notice that I could have written the previous three sentences as one long sentence. Instead, I broke it into three simple sentences.)
Use the active voice when you can. A good rule: Minimize the proportion of your sentences using the verb 'to be'. For example, write 'depends on' instead of 'is dependent on'. More hints here.
Treat abstract sentences like a disease. Cure them. For example, write 'species diversity declines at increasing latitude', not 'species diversity is related to latitude'. Make your sentences convey information.
Use bullet lists wherever they improve comprehension and readability.