This past season was the first time that I played, and it was a learning experience to say the least. A few things that I learned - some may be obvious to folks who are more seasoned:
Look for guys who are classified as a deeper position from a fantasy perspective but play in a more forward position IRL. Two examples from this past season were Lundstram from Sheffield United (classified as D but played as MF) and Martial from Man U (classified as MF but played as ST). You get more points for what they do attacking wise and get the knock on from defensive stats.
At the beginning of the year, I was constantly tinkering trying to get the perfect (and almost balanced like IRL) 11 out there every week. I was basically trying to have a team with some strength at all positions, but maybe less emphasis on superstars, and hope that they all hit. I had better luck when I just went all in with as many big names as I could afford and then filled in around them.
Defenders from smaller clubs - particularly those who are just looking to scratch out low goal results - who basically never leave the field can be really valuable. They may not be flashy, but they are effective.
I didn't think I knew when was the best time to use the chips, and I still don't think that I do now. I don't know if there is some strategy there that I am just missing.