Cleaning is not necessary with smokeless powder unless you have cases that were ejected into the dirt. Then you want to get the grit off before they go into your sizing die. Wipe them off with a rag dampened with some of the mineral spirits.
Some people don't clean until after sizing because the case should be decapped for that, especially for liquid cleaning, or they will still be wet in the primer pocket when you knock the primer out. But to my mind the main point in cleaning to get the grit off, so that sequence makes no sense to me. Board member Humpy has made a good argument that getting hard carbon out increases barrel life, but that requires either ultrasonic cleaning or tumbling with stainless wire media, so until you are ready to go to that extreme, grit removal and polishing for appearance are all you can do.
I bought the $10 Lee universal decapper, and I use that to decap cases for liquid cleaning prior to sizing. The decapping pin in the sizer then does nothing. You can also usually adjust the decapper on your sizing die down far enough to decap without sizing, but if you do that, you'll have to move it back up for sizing. The separate die just saves having to make the adjustment. It's no big deal, though.
The old NRA liquid cleaning formula is white vinegar and salt. Depending how many cases you have, put a quart or two of the vinegar into a an empty plastic milk jug. Add two tablespoons of salt for each quart. Cap and shake until the salt dissolves. Drop the cases in. They should be covered by the solution. Tap the jug to dislodge air bubbles. then let it sit about 20 minutes. Shake it up well and tap it for bubbles again about 5 minutes in and again about 5 minutes before the time is up. Pour off the vinegar and salt. Rinse and dry.
The above method will leave cases tarnished after they dry, so it's not the best thing for appearance, but it does get dirt off and loosens a good bit of carbon, and the acid reacts with carbonates in the primer residue, which fizz in the acid, helping break the residue up a little, so this does help.
Some folk now use a 5% (by weight) solution of citric acid instead of vinegar. This shines a lot better. Some also put in a teaspoon of dishwashing liquid (Humpy likes Ivory brand, especially, though I've used baby shampoo and it seemed OK). Some use the detergent but not the salt. So you have a number of variants to try here.
If you eventually get a tumbler, it will clean the grit and polish the outside without first decapping, which is how most progressive press owners do it. I prefer to clean primer pockets in rifle ammo and don't worry about it in pistol ammo unless I am getting a lot of high primers coming off the press.
