Welcome to the forum!
I also second that mediating often is a good way to build yourself up for not only communicating with the gods you wish to (as there are many, many of them) but strengthening your magic. There are multiple different techniques on this forum to help develope your astral senses, which will be helpful with things like evoking a deity. A form of divination can definitely be handy at first but learn to go beyond that once you master it so it does not become a crutch.
Researching everything you can on the particular spirit will help you immerse yourself into the current of that spirit to help bridge the gap between you and then. However, dropping expectations of that spirit from the research prior to ritual is just as important as the real deities will tend to surprise you instead of fitting perfectly in its mythology (those tend to be egregores). Asking for them to list their abilities is a good way to weed out the real spirits and the imposters.
I recommend clapping or knocking on the wall just before starting and right after ritual to mentally tell yourself that anything that happens is part of the ritual. Whatever does, take it as it is in that moment (save the questioning and analyzing until after you are done). Learning to banish and cleanse an area beforehand is also wise. While there is usually no danger, their energy might not be what you want hanging around the area afterwards, but that is your choice.
Phew, I think that is my basic suggestions lol. Welcome again!