I don't leave with any form of protection, if I run into trouble I deal with it head on, I'd rather spend more energy on traveling and experience than worrying about a barrier or some form of guard. There is one time while I was sleeping, I was yanked out of my body by someone who I have constant problems with (I won't say who for one obvious reason), he pulled me out and I was astrally conscious, I first thought it was all a dream still but I was feeling the strangling like it was physically happening so I quickly realized it was really happening. So after a few tricks that worked only temporarily (like spikes sticking out my neck to stab his hands to make him let go, he grabs again, then I asked for help from my first life time being (wisest one so he's most likely to be my main guide) and all he does is give me just enough energy to wake me up more and then I took care of the situation. Boy, was I thankful after that, that definitely shocked and ticked off my other selves a lot. We planned a few counter attacks for the next time he decides to do that.

Whenever I meditate I mostly just call out the name of whoever I need to communicate with to learn whatever I want/need to learn. I don't see colors, some times I accidentally grab information from my guides'/past life's past or more. They don't know I'm getting it until I ask about it.