Think of it like building a muscle. You are opening up an area of yourself that hasn’t been used for most of your life so it’s going to take time and effort to shake off the rust, so to speak.
Practically, work on you trance, energy work, and scrying.
Spirits can help to open the door by influencing your energy and unblocking chakras, but you will still need to build up the muscle with some effort.
Spirits that can help: Sastan, Raziel, Azazel, Mepsitahl, Satagraal.