As kind as it may seem, sadly you can not help a spirit to cross over.
Because the second you leave your body you have crossed over, unlike a physical body can only stay in one realm, Spirit can move through several realms as it is pure energy.
Theoretically, we cannot assist any crossover because we cannot see or yet know where we are sending them, for all we know we could be sending them into the bowels of Hell. Possibly all that spirit needs is to be told they can go wherever they want to be, as they are in a new existence, one more wonderful than ours. But chances are, you won be telling them something they don’t already know.
I used to think l was doing a good thing many years ago in assisting those who asked me for help. That was, until my Spirit Guide Sowella told me that was not up to me to help, it was the choice of that Spirit. However the reality is, they are spirit and spirit is energy, that can be anywhere it wants to be.
So even though we can assume we are helping them, truth is, we are only doing so for our own ego. As that spirit can leave, but only if it so chooses to do so, therefore if it can choose to leave, it can also choose to return.
So until we can factually see where that Spirit is going, we are not authorised to promise them we can help, no matter how spiritual we are.
The best you can do is pray that Angels will step in and provide the assistance that spirit requires.
Just because some spirit say ‘help me’ they are not necessarily wanting or needing help in crossing over, but may simply be asking for help in letting their loved ones know they are still very much alive on a spiritual level.