I do grimoire work and work with spirits in a shamanic tradtion. ( nordic/celtic) I'd start with an alter which is dedicated to your ancstors and the dieties you work with. If you want to do spirit conjuring use a grimoire and make sure you follow it exactly. Your actual beliefs don't matter so much when your doing that, so much as your cultural background so if your from a non european/ western asian culture you'll have to go a different route.
The shamanic path is something that your called to do and not something you choose, the spirits decide they want you to represent them and make it very impractical to say no.It often involves a physical illness which forces you into that path. Once your there you are trained and you go on your way. Once the initial crisis is over it gets much better.
Both require initiations and securing specialized items which are often difficult to get and can be expensive. The spirits if they will allow you to work with the grimoire help you to secure the needed materials. Part of the grimoire initiation process involves securing the unusual items. The same thing happens with the shamanic path but not to such an extreme extent. But the grimoire path is one that can be chosen.
A group can be helpful but with this sort of thing a lot of solitary work has to be done. It's not something someone can do for you. It's not like a church where if you follow a formula do this do that everything will work. best thing I can suggest are two things; First do a lot of reading on your own but do your own thinking. Reading isn't the end all you have to formulate a relationship with the elements of your magical system. Second if you feel your in a shamanic crisis that is you have a physical illness that cannot be explained and spirits coming at you from all angles to the point where it's mentally disruptive do reading in regards how to go foward and answer the call. you have to learn how to handle the spirits who are attracted to you and have chosen you to work for them You have to work for them in a position of authority as well as learning from them. It's a difficult balance to maintain.