nicho, before 2008, I would say just go for it. In August 2008 there was a big mud slide that created a new rapid called Joe Hatch (check youtube for lots of videos). This is a must scout rapid especially for new boaters.
That said, Deso is the best training canyon for expedition type rafting. It starts FLAT, and I mean the paddle out on WW is a walk in the park compare to first 25 miles of Deso! So launch early from Sand Wash, or pay the price of the winds.
After you get the first 25 miles under your belt, the canyon starts to drop slowly and the rapids get bigger as you go further. So it's perfect to test your skills and warm up before you hit the bigger stuff.
The mandatory scouts I would recommend for new boaters are:
Steerridge (scout is on the left steep bank, right as the river starts turning left and you hear the roar, don't miss it). The easy run is on the river left. A very obvious tongue, straight forward, big wave train. The right channel is open in high water and has a fun hole to punch through.
Joe Hatch (a mandatory scout on the river right) you have plenty of time to get to the right once you hear the roar. Go past the huge standing pool of water on the right and an island, then hug the right side and find a good spot to pull over to scout, there are a few scout points now. The Joe Hatch can be run on Left or Right channels. Left channel is the biggest and flipped a lot of folks, but it's more straight forward. A huge wave train, passing a big hole on the right and then pull away from the Rock wall like Sock It to Me. The right side is a rock garden, at high flow everything should be under water and might be an easier route for newer boaters. Scout it.
Coalcreek - This one used to be the biggest rapid in Deso until Joe Hatch evolved. The scout is on river right, right before the river turns right. A single scout point in the bush, so don't miss it. Coalcreek is a two channel run as well. One is on the left, which is the easiest, but the current pushes you to the right, so you just need to muscle a bit to keep in the left flow. The right current will put you into the Thunderous Hole, at high flow it will most likely be washed out, but in the lower teens it's a bit hole to punch! After you get through the Thunderous Hole just stay off the right wall and you are home free.
Wire fence - The scout is on the river right at the end of a huge eddy on the right. It's self explanatory once you see it. Just stay in the current, drop over a boulder and zig zag through some exposed rocks.
Rattlesnake - is the last rapid that could cause some havoc. The current really huge the right wall and there is some pressure pushing you against the wall. So just avoid hitting rocks/wall as you are going down it.
There are a lot more wave trains along the way, but most are 2s maybe low 3s.
Have fun, hopefully I will be launching about the same time as you