I communicate with them in many ways but usually through prayer. The concepts & thoughts you are getting are god, the angels and your guides, listen to them and they will tell you the best way for you to communicate with them. The Angels love sending me Angel numbers and have been since before i started to communicate back with them.
As for being afraid of a being communicating with you that is not a being of light, you need to protect yourself before going into a meditative state and you can ask for them to protect you in your sleep and everyday life as well. Simply ask the Archangel Michael, to be with you, surrounding you with love & light, protecting you and only allowing beings of light & the Holy Spirit to come to you.
Whenever I do any spiritual work that puts me into a mediate state & before I go to bed(I lucid dream from time to time) I ask him to be with me and than thank him. Here is an example of asking him to be with you while you meditate.
Dear Archangel Michael,
I ask you to please join me as I go into this meditative state to try to connect with my guides and angels. I ask that you surround me and my loved ones with love & light protecting us from those not of the light and only allowing beings of love, light & the holy spirit to connect with me.
Thank You, Dear Michael, I love you , Amen
By asking him for help you are asking him to act as your bouncer so to speak and he will not allow any beings to come to you that are not who you are looking for. The Angels and your guides will never lie to you so if you ask him to shield & protect you you can be sure that hose who you are communicating with are truly who they say they are. You can change the prayer to suit your particular needs of the moment and it will still work. If you are fearful even with askign him for protection you can add that you wish for him to help you not be afraid & he will gladly & lovingly oblige.
There is a member here named Bing who has created a spiritual library, in the library you will find information on Archangel Michael and the other angels. I encourage you to check it out.
Do not be fearful and have a blessed day!