I am not an English teacher, but common usage would include:
I will need your help... (generally means you are committed to doing something but will need help at some point in the process...)
I would need your help... (generally indicates I am not yet certain I will be doing [whatever], but if I do, I will need your help to accomplish it - so my decision may depend on whether you can help)
Can you please help... ("can" is asking if you are able to help...)
Could you please help... ("could" is usually asking if you are willing to help...) and Would you please help... is asking you directly to come and help...
Others may have differing opinions on the inflections of meaning in these questions...
- For Teachers