No amount of reading or watching videos will make up for riding. I come from thumpers, so standing on the pegs is my preferred off-road riding style, many from 4 strokes like to ride seated. My recomendation is find long gravel roads and ride. I am not that familar with the Multi-strada, but turn off the TCS, throttle is your friend, and don't let the squirm of the rear whell scare you. If you choose to stand on the pegs, use your knees to squeeze the tank to turn the bike, keep your butt toward the back so the weight is off the front wheel, and work on throttle control. Smoother is always better, and momentum is your friend.
Hope that helps. I had a whole crew of newbies with me in Ouray a few weeks back, and took them on a 90 mile juant across the Divide Road from Ridgeway to Whitewater across the Uncompaghre Plateau. Long straight aways, twisties, loose gravel, hard pack, the whole gambit. Everyone was ripping the last 30 miles like maniacs, an we only had one (1) goof, and that rider was on street tires, but no serious damage.
Gravel opens a ton of adventures to you, don't be afraid to explore. Also a good tire will inspire confidence, I prefer Heidenau K60's, long life, well mannered on the street, and eat gravel.
In this video, the guy in front of me was one of the folks from the previous day
[video=youtube;ZbGhOntdyVE]https://www.youtube.com/watch?feature=player_detailpage&v=ZbGhOntdyVE&list=LLEnldbT3sbT2_zgXM2YFXsw[/video]