Why are you asking? Really? You know for me I do not like or work with some Gods but other people Adore them and work with them. People are different and everything. You need to STUDY and by this study what yo0u think you may like. Personally The Titaness Hekate was one of the first beings I worked with when I became a solo pracitioner. She is a Good being to work with. But do not ever make her cross. RESPECT what ever you plan to work with. And do not summon them to ask Questions. As for some Beings do not like being asked questions by someone who is not even dedicated to them. Or Took the time to know there lores. It is also good to give an offering One they will like from what you learned from yourstudies.
Hecate was one of the first I worked with too. I first developed a relationship, studied her, called upon her politely- A lot different than summoning which is commanding her presence. I left her offerings, I asked her to join me if she so wished in spells. She always did (Or I felt some boost in the circle so to speak), there was no need to summon or invoke her. I would invoker her if it was necessary, but it never has been.
Isis is another deity whom I love, Zeus, Pan etc. The above all applies for them too.
In short I have never met a horrible deity, then again I haven't invoked every single one. Even deities who have a bad reputation such as Set I have found to be not so bad....
All Gods and Goddesses are friendly,however that status of Friendly depends on several elements:
-Respect you have to Him,Her or Them.
-Their views of you as a human,person and a worshipper.
-Your gifts(Optional;but gives you that special plus in Their Hearts)
-Your prayers(Prayers when you just say Thank You,instead of constantly asking for something)
-Your Love for Him,Her or Them.
-Your loyalty to Him,Her or Them.
-Their favor to you(Gained by proving your worth to Him,Her or Them)
When someone says for example Hecate is friendly,it depends on how that person is with Hecate,She won't be friendly to everyone.
Gods and Goddesses have a Neutral stance to all people,until and if those people show that they either Love and worship Them,then their stance becomes warmer towards you OR if you hate Them,Most of Them won't have a changed stance,Some may hate you back.If you harm a worshipper of one Religion then that person's God,Goddess of More of Them will hate you even if you don't realize it and can and will harm you back one way or another.
So I strongly suggest you consult more about a ceartin God and/or Goddess OR Gods and/or Goddesses before making a first step towards One or More.If you'd like I'd like to offer you help.
Invoking and/or Summoning One isn't a good idea if you are not good to Him,Her or Them.
Do you already belong to a particular religion? If so your best bet is to call upon the God of that particular religion rather than just trying to talk with a God or Goddess you don't even know. Many Gods may be friendly if you have a relationship with them. But any of them can also become extremely annoyed if not approached with need and respect.
Whether a god is friendly depends on your relationship with Him/Her. Once you establish a mutually beneficial relationship with a specific deity, that deity will be friendly toward you.
when calling on a deity, be respectful, all deities will be kind if you are kind to them. Do not summon, summoning is commanding their presence. Instead, ask, pray, invoke. The degree of kindness they show depends on:
1) an offering (not neccisary but it's nice)
2)the devotion you have shown towards them, do you pray to them everyday? Are they your patron?
3) their understanding of you, here's where medusa went wrong, she was going to be raped on the alter of Athena, who is a maiden, I'm not saying that Athena is not compassionate, I am saying that you must look at the circumstances, if she had gone to the temple of Persephone, who had a similar experience of being forced by a man, or demeter, persephone's mother, who missed persephone sorely, they would undoubted protect her.
4) are you worth their trouble? Have you proven your worth to them?
5) do you truly believe in them?
6) be sincere. Insincerity makes everything worse.
7) reseach this deity, are they known for being prideful, arrogant, a trickster or a tyrant?
8) worship, worship, worship! Worship is a great way to strengthen bonds with deities.
9) are you sure this is what you want? By doing the above, you are likely to be shown kindness, but that is only on the surface, if you're working with a trickster like Loki, do take into account that he has been tricking humans for centuries and have much more experience than you. So take care and be pedantic, working with them, you should not allow them to twist your wishes.
I'm sure you could look up the word "invoke" in a dictionary rather than expect us to do that work for you. But "invoke" is defined as "To call on (a higher power) for assistance, support, or inspiration:"
An excellent site to read about the Gods from a variety of different pantheons can be found at http://www.pantheon.org/
Invoking is what you should probably be doing instead of summoning. Summoning is demanding their presence, invoking is simply asking them to be there and to assist you. It's much more polite if you ask me.