Get minnows at Kilmers or wherever you buy them and at least what I've heard, the best luck on catching crappie besides night fishing is early morning like 5am to 7am or something crazy like that. Launch at Windy Hill and I've heard the mouth of Salome cove or in there has some but haven't fished it much. For the past month, a flotilla has been forming across from the Schoolhouse ramp. If you're not sure where to go, go where the rest of the boats are and you're not looking for fancy bass boats trolling up near shore casting usually but a different crew of boats who are trolling usually a little further from shore at least this time of year. Many people troll 0.5mph to probably more like 1.0mph so having a GPS or something to measure speed would help. Use your find to see where the fish are but there's thought that crappie in Roosevelt are usually in the 12-15ft range so whatever you do, get your lines down that far depending on your speed. At least a few weeks ago, the flotilla was fishing in 25ft to 35ft of water. Don't fish too deep as crappie look up and don't often look down to get bait. I often try to get my line brushing the tops of the undercover brush. Many people use 1/16oz jig or 2 jig setup (spaced several feet apart) and a weight above a swivel to get their lines down a little. Try chartreus or I think a variety of colors for the grub that you put on your jig. Grub could be 2" grub. See if you can have someone else on the boat try completely different setup in case this one doesn't work you have variety out there and once one catches on, be willing for rest of boat guys to switch it up. You could try a slip bobber with just a minnow on a hook and a little weight to get it down and maybe troll slower. If no boats at Schoolhouse area, try Why Cove area not inside as much but at mouth. If not there, I've heard Tonto end may be the way to go instead so you may want to try there and I'm guessing they're all at the end. You'd need to ask locals to know whether to try Tonto or Schoolhouse first.
If you're not sure of all of these locations, you need to buy a map of the lake or good GPS with locations in it. Fish-n-Map sells a good one.
I've only seen big crappie caught out of Roosevelt but if you catch anything 10" or less, toss it back.
If no crappie at some point, try larger black jig with minnow. You might at least catch some other fish while trolling.
Oh and check the water temp. If water temps are getting up to 62 deg and staying there, crappie will be spawning so switching it up and going to shallow areas and casting in would be something to try.
When you return, be sure and post a report in the Roosevelt lake section on how you did and what you ended up trying.