I always play with a typical Champions League 4-4-2 with a backbone, which means.
......GK......
RB CB CB LB
......DM.....
......CM.....
RM.........LM
......SS......
......CF......
But I have a trick, once I get more than 1 goal up, I change to the following 4-2-4
......GK......
RB CB CB LB
......DM.....
......CM.....
......SS.....
RW..CF..LW
Because you're 2 goals up, the opponent will want to score to get back into the game, and will leave a lot of space in their defence. You can either compensate for this by focussing more on defending, but that usually leaves you out of control of the match, so I shove 2 extra attackers forward to keep hold of this game. Once you conquer the ball in your own half, your 4 attackers will be ready and waiting for them to tear apart the remaining defenders, which shouldn't be more than 4, maybe 5. The trick now is to become aware of where the spaces are, pass the ball forward and keep your eye on the minimap to see which winger has space, and use it. Don't be afraid to cross the ball over the pitch if the other winger has more space, and play smart. Realize you are the one winning and you have all the time in the world, just don't waste chances. 3-0 is better than 2-0, and it will open up yet more space.
I've been using this tactic mostly in the Master League, but it works just as well online.
Speaking of Master League, my ultimately goal is always to win the D1 League, the D1 Cup and the European Championship (CL) in the same season. Only then I consider the game finished, and I start over with a new team. So far I've managed this feat with 7 teams, 3 of which I managed within 3 seasons (Ajax, Tottenham and Barcelona). Right now I'm working on Arsenal, on my fourth season, the D1 league is in the bag with 5 matches left to go, the D1 Cup final is reached after beating Man Utd twice with 4-0 (8-0 aggr), and the CL final is reached after beating AC Milan 3-0 and 5-3 (8-3 aggr).
I use 10 minutes per game, on Top player (5 stars) for both the game itself and the master league setting.
