The reward depends on the value of your tokens.....structure your bounty program (Facebook promotion, YouTube, forums, articles and posts, twitter etc..), rate the directions according to the target coverage, predicted conversion etc.., and if your researches and examples of a number of other similar bounty programs still have't clarified the picture, just try to assume an adequate price, for which you would participate in such reward program. For example, 20$ for 1 article with a link (2000 words)..is it attractive and ok, or it's to expansive for your ICO's budget, 2$ for short post, 10$ for translation and so on...just explore..When you begin to work through your campaign in all details, set the goals for your program, the term etc..it will be easier to specify the appropriate prices. Good luck!