Welcome to the forum.
1 - Read this post. How do I get started in summoning magick and make contact?
2 - Banish before and after every ritual. You will know when you don’t need to as you gain experience. Banish every day if you think you have an attachment.
3 - Read the instructions in our tutorials and use the search for your intended entity to red around the subject.
Use the search with “letter intent tutorial” and there are a few. Read and compare everything yo can find and ten design what works for you. E.g. this one tha I found in 2 seconds - Letter Of Intent - How To Evoke A Succubus/Incubus *update*
We are all students here and far too busy doing our own magick, but to an extent, this entire forum is your mentor, it’s a huge community with 14 years of newbies asking the same questions over and over, answered in every way you can imagine - READ it - you will learn a lot. Do not wait for people to notice a post, help yourself to the info as and when you need it.