Some of this is also covered in the FAQ about demons, but here's the version for people who don't want to work wtih demons.
Do I need anything specific to start working with spirits or worshipping them?
Nope! If you don't have the money to buy stuff for an altar, you can just do meditation sessions with them if you want, or draw their sigil on a piece of paper to invoke them. However, having props can definitely help, and I personally get the best results when I do at least a simple ritual for first contact or for important things. Some people love going all-out with devotionals or doing proper ceremonial work, other people keep it simple and might have a candle out at the most. It's all up to you.
However... You're allowed to get creative! Make a Minecraft Temple! Play PVP games and dedicate your matches to your war deity! Write a fanfic and show it to a muse spirit! Even a shelf that just has random knickknacks that remind you of your chosen spirit to work with can be a good altar.
Are deity identification services a scam? (e.g. "What deity wants to work with you?" tarot spreads)
Yes and no.
You don't need outside services to determine who you should incorporate in your practice, but sometimes a nudge in a specific direction can help people with choice paralysis. If the reading ended up helping you as intended, then in the end would it really have been a "scam"?