If you are interested in working with Greek or Egyptian deities, I would recommend going with Greek first. Egyptian deities are extremely stern and intense beings that have very bland personalities. Their company, although educational, will not be enjoyable! ....at least that's my opinion through experience. Don't ever forget to thank Greek deities however! If you're familiar with the mythology, many people suffered terrible fates for forgetting to thank a Greek deity! They're very generous, but they absolutely hate when people are unappreciative. Don't forget, the papyri were written by people who worshipped these deities and gave offerings. They didn't just do rituals commanding them and call it a day.
I've read some of the papyri and I would suggest taking from it only the general idea as to how to approach and work with these deities, and not as an instruction booklet. Most higher beings are more agreeable when you take the time and effort to approach them in a way they were approached by the magick practioners during the period of history when they were most popular.
[Thoth] contrived...for Cronus the ensign of his royal power, having four eyes...and upon the shoulders four wings...But for the other gods there were two wings only to each upon his shoulders, to intimate that they flew under the control of Cronus.