Day Six: The Power of Prayer/Reciprocity
I think reciprocity is the most important thing in paganism, full stop. Typically, if I pray to a deity and the outcome is favorable, I'll thank them by giving them an offering or doing something else I think they would appreciate. Sometimes I just give deities offerings because I want to show appreciation, which has the benefit of strengthening our bond, for lack of a better phrase.
If you show appreciation to the spirits, ancestors and gods, I feel that they will show that appreciation back in some way or another. You won't get punished for not showing them appreciation, just to clarify for any non-pagans reading this. Everything I do is because I personally want to do it, not because I feel like something bad will happen if I don't. Giving offerings may make a deity more likely to help, but not giving offerings doesn't make them more likely to harm.
I once read a pretty good explanation of reciprocity (in this context) on a Heathen website, if I recall correctly. I'll link it here if I find it again. It explained it like this: Let's say you babysit for a friend so that they can finally have some time alone with their significant other. As thanks, they cook you dinner. Then, as thank you for dinner, you offer to give them a ride to an event or work or where ever. Then, as thanks for the ride, they help pay for gas...and so on. It's like that. Of course, sometimes people will go out of their way to help people who won't help them later, either due to not wanting to or not being able to. I personally help friends who aren't able to do anything for me later, simply because I love friends.
I do have a critique of this, and it's that I don't think you need to build that much of a relationship with...any deity, really. As long as you hold up your end of the bargain, I think it's fine. I have deities that I do have this sort of rapport with, whom I tend to go to when I ask for help (ie Apollon, Skadi, Odin, The Dagda), but I also will ask deities whom I have never once prayed to for help sometimes and just make it clear that I do intend on giving them proper thanks if things work out for me.