The writing in this post is purely my own opinion and practice. Please don’t take everything I say as truth in your practice. Do what feels right for you!
Many people worship, revere, or work with deities regularly. In my practice and experience, there is a right and wrong way to approach the Gods to ask for their assistance. One thing that you want to make sure you do - especially if you work with that particular deity regularly - is to give relevant and wanted offerings. Now, these offerings are going to depend completely on the deity you are connecting with, and research needs to be done on your part to make sure you won’t offend Them with your gift. For example, I would never offer a piece of steak or leather to Brigid because the cow is sacred to Her.
Note: Please keep in mind that most of this comes from my own personal practice of Irish Paganism. Not all concepts, ideas, and beliefs will apply to everyone. However, the act of giving offerings is typically the same in any spiritual practice.
Why do you need to give offerings?
Think of it this way - you would never go up to a stranger and ask for their help with part of your life, or ask for money, or abundance, or wealth. The same concept applies with the Gods. If you don’t have a relationship with that particular deity, they are more likely to ignore you. They could accept your request, but it will likely come at a price you might not be willing to pay. Giving offerings is one way to start the process of building a foundation with a deity - one of mutual respect and reciprocation.
What do you have to give?
The Gods won’t always ask for a physical item - food, libations, coins, etc. Many times all they want is your time. They want you to prove that you are willing to do what it takes to meet the requirements to work with them. Lora O’Brien from the Irish Pagan School has a YouTube channel where she talks about giving her time to Manannán mac Lir by taking a swim in the ocean once a day for a week (I believe this is the correct time frame). Manannán mac Lir is also known as the Son of the Sea, and this is what He required of her in exchange for His help. Now, it might sound silly, but this was in Ireland in the middle of September. The water was freezing - and it was a sacrifice of time and comfort for Lora.
Of course, the usual things can also be given as offerings. Many Gods enjoy alcohol of some sort - I’ve read that Brigid enjoys an offering of whiskey every now and then. Sometimes water will do the trick. As far as food offerings go, this will depend highly on the deity. Like I said earlier, I would never offer any cow products to Brigid because the cow is a sacred animal to Her. If you’re having trouble figuring out what to give your deity as an offering of food or drink, look into their lore and their myths. See what they enjoyed in their stories. You could even just ask them! Some Gods will not be offended if you don’t know what to give them. However, approach this with caution depending on the deity.
For example, I do not worship or work with deities in the Greek pantheon. However, I know enough of the lore and myths to know that if I was to give an offering to Dionysus, I would probably give alcohol of some form and some fruit. Or throw a party. These are things that He would enjoy based on his lore, myths, and stories.
How do I give the offering?
Again, this is largely going to depend on your tradition and path. However, I do have a basic format for giving offerings to most deities and this is the personal method that I use myself. Since I worship Brigid, my offerings to Her vary between candles and incense - sometimes heavy cream. I stand in front of my altar with my eyes closed, focusing and listening to my own heartbeat and the world around me. Sometimes I get flashes of thoughts that aren’t my own - sometimes I don’t. When I feel calm enough and grounded, I light my candle. I don’t have a standard chant or prayer that I say, but I do say something along the lines of the following:
Blessed Brigid, Keep of the Sacred Flame - Please accept this offering. Thank you for the protection you have provided for my home and hearth.
I’m also learning the Irish language, so I’m in the process of trying to create prayers in Irish. This particular one translates (using Google) as follows:
Bríde Beannaithe, Coimeád an lasair Naofa - Glac leis an tairiscint seo le do thoil. Go raibh maith agat as an gcosaint a chuir tú ar fáil do mo theach agus do thinteán.
Since I work from home, I keep the candle lit all day unless I have to leave for some reason. When I have to put the candle out, I don’t blow it out. I put the lid back on the candle and snuff. There isn’t a particular reason for this besides being told by Brigid that I shouldn’t blow it out.
If I give offerings of food or drink, I try not to put them down the drain or in the trash when the Gods are finished with them and no longer need them. I give them back to the Earth whenever possible. However, I do recognize the fact that this is not possible for everyone. So please, do not take this practice of mine as fact. Dispose of your offerings in a safe manner for wherever you are. If you can pour out the liquid in your garden, that’s wonderful. If you have to pour it down your drain, that works, too. Please do not leave anything outside that would be harmful to the local wildlife or the planet .
I hope this has helped you in some form. I do plan on doing a video on how I give my offerings to Brigid on my YouTube channel one day - just not quite yet.
Do you have deities that you give offerings to? Do you have any questions? I’d love to hear your experience!
I’m glad you found it helpful.
I think the only way to know for sure would be to test it and experiment!
Sometimes I can just go on and on… and then things tend to not make sense anymore or I end up on a completely different topic!
Ugh. I feel like this should have been obvious to me upon hearing the term “sacred cow”. 
I still had a lovely ritual with Brigid, though, so I don’t think I greatly upset her.
I’m glad I was able to help calm your mind a little bit, and that you found solace with Brigid. Sometimes our bad days can make us second-guess the things we do, even if we intuitively feel like we’re doing just fine. I’ve been there!