I have found a paper again which I have read at the beginning of my LBM research. I can only highly recommend this article, since it contains many relevant aspects and also some subtle issues on the simulations parameters and unit conversion.
Y. T. Feng, K. Han, D. R. J. Owen; Coupled lattice Boltzmann method and discrete element modelling of particle transport in turbulent fluid flows: Computational issues; Int. J. Numer. Meth. Engng. 2007 (72); 1111-1134
or click here.
I hope this will help you, but I am sure it will.