Hey Dude,
Thanks for the watch
Tutorial wise, theres no really good flyer/poster tuts out there as far as im aware. What i would surgest is that you get all sorts of good technique tuts done and then use the stuff youve learnt in your work.
Practice practice practice is the key, if you can do something new every day, within a year thats 365 different techniques you'll have down giving you a pretty large suitcase of tricks.
Also browse the "design & interfaces" section on here daily, theres some amazing artists here which make me look terrible so i surgest you check them out and get some inspiration and try to work out how theyve done different things! If you cant work it out, ask them, 90% of people are really friendly and will help you out!