The issue of focus is a fundamental challenge of macro work, and there are a variety of 'solutions' that can be used to try to address an inherent problem.
As a rank beginner, all you should attempt is first ensuring that your primary subject features are in sharp focus (and with no camera motion blur). What post #7 mentions are fundamentals employable in any aspect of photograpy, their uses simply are singificantly more important in macro work.
And THEN slowly adopt the use of increasingly advanced methods for increasing the amount of the subject seen with sharpness. Each takes time to master.
Your issue of highlights blown out is not specific to macro work, but inherent to photography of objects (sometimes referred to 'product photography'). That is, generally speaking, dealt with by control of subject lighting brightness range.. It can involve metering very selective areas using spotmeter to assess the brightness range of highlights vs. shadows, and controlling the lighting to better fit withing the range which can be captured by the film:
- (already mentioned) the use of light reflectors to add light
- (and non-white panels to cut light reflected to the lens' view)
- and/or use of angles of subject and/or wisely in the placement of light sources.
This can be quite simplistic, or can be extremely complex and time consuming to implement, in part due to inherent technical complexity of the object being photographed. Again, methods used can take time to initially implement, and more time to master.