I generally have 4 phases on each game. I've followed this recipe since FM10 at least.
1. Play with my favourite teams, 10-15 seasons with Liverpool, 5-10 seasons with Atletico (new save ofc), and then the same with my local team.
2. Start out with no experience and start in the lowest possible division. Doesn't matter which country, just that you're in the lowest division. Then I choose between staying at that club for 10-20 seasons, or if I accept offers from other clubs and create my legacy as a manager that way.
3. Updates. This is typically around february when the transfer window closes (and the league is finished in Norway). I like to test out the new players my team has signed and typically plays 5-10 seasons on a couple different saves. I also do this of course when the summer window closes.
4. Challenges. This is the phase I'm currently at with FM15. I like to check out this site and see if there's anything that excites me in terms of custom db's or I simply make my own. There's a lot of things that can be done, from legends to financial challenges. On FM14 I created a save where I recreated Rafa Benitez' Liverpool side in the editor and played for 4 or 5 seasons with that team.
At the moment I'm playing with a custom db I've also made myself where I've changed the Norwegian league system so that all the clubs have finances like Premier League clubs, and then I'm going to see if Norway can become one of the top nations in europe and also if the National team benefits from it. I'm currently only at seasong 3 but I'm gonna stick with this one till FM16 comes out so hopefully I'll get to play a few seasons.