Your going to get the gamut of opinions on this one, here's how I do it.
Hot water and Tide detergent and a few long bottle brushes with stiff bristles to clean the inside and all the galleries, keep the engine wet while doing this and have some spray lubricant handy for when you are finished. Once done spray with lubricant while still wet and then use an air hose to get the last bits of water out of the crevices. Now that you have done the majority of the block you can concentrate on the bores. I take a very fine scotchbrite pad (white) soaked in automatic trans fluid (doesn't matter what kind) and scrub the bores and journals to remove any imbedded particles. After doing all the bores and journals I then take a cotton flannel cloth soaked in trans fluid and start wiping the bores down, you might be surprised to find dirt still coming out of the bores pores with each wipe. Change rags often for each bore to prevent contaminating your clean bores. After your done go over each bore with a clean lint free tissue to check your work (I use lint free Kimwipes). If you find any dark spots on your tissue do that bore again. You are done, now bag that sucker before it gets dirty again!
I know this is elaborate but it has become a ritual for me and usually takes an entire afternoon to complete but at least I know the engine is clean. Feel free to add to this if I missed something.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”
— Han Solo