use of graphics and lines spring to mind. Depending on the data use things like pie charts. other than graphs where you need to colours for different datasets, keep colouring simple and light, use grey rather than black.
for fonts, choose a standard one, perhaps show headers in a slightly darker colour and perhaps bold to the data below
Also consider how the report is viewed - printed or screen? and if printed is it going to be a colour or black and white? if screen consider a darker background and lighter text, also avoid horizontal scrolling, so be aware of your users screen sizes.
If you are a company, they often have a standard template for things like powerpoint, so take some ideas from there.
less is more, space things out if you can, don't crowd the data, emphasise the important data, don't give lesser data the same weighting on the report.
Investigate the use of the report property me.line which when used in code can draw a line of a given thickness and colour across all sections (headers, detail, footers etc) - much neater than have textboxes formatted and lined up - great for shading a totals column for example