I might disagree here if only to point out that in attempting to command any such powerful spirit or entity you will typically run into resistance unless they want to come along and teach you a thing or two, or otherwise take pity on a naivety.
Otherwise, you can do whatever you feel is appropriate. Take some time to learn about Hera, and what sort of offerings she enjoys or how she prefers to be approached. Develop a bond first through an understanding of her nature, and then make an offering in this manner (could be something as simple as flower petals, wine in a bowl, etc. though I'm not familiar with specifics for hera) and ask her for her blessing or wisdom and so forth. You never know what kind of answer you'll get.
It's often wise to take precautions to protect yourself magically as well in these circumstances. However, naked devotion (not going in armed and armoured, in a manner of speaking) is sometimes appreciated by spirits and gods (goddesses) as well.