Here are 2 Bundesliga squads:
4-3-2-1 - http://www.futhead.com/15/squads/18973799/
I have a similar (but more expensive) team with the exact formation and it can really work wonders. The 4 at the back is really good for holding against counterattacks and the relatively strong and all rounding CMs can hold the midfield well while presenting passing options for the forwards. The 3 attackers give you plenty of options upfield and are all very good for their price. If you still have room for an upgrade, I'd say swap Jansen with Ricardo Rodriguez. And once you have some more coins, try swapping Großkreutz with Piszczek to round out your backline. Overall, I feel like it is the best Bundesliga squad for under 20K coins.
3-5-2 - http://www.futhead.com/15/squads/18975629/
Once you start earning more coins, I would suggest you make this as your second/fitness squad. This is my second favourite formation in the game and it gives you lots of depth in the squad. The defensive wingers can fall back to help out the backline, making it effectively a 5 in the back or move up to help out the midfield, to pack it and present you with lots of playmaking options. It takes some getting used to at first but try to play some offline games with it in order to nail it down. The key to using this formation well is to set instructions for the team. Make sure that your wingers are set to "return on defense" which will make them run back to form a back 5 when the opponent has control of the ball. Also, since you already have 2 CDMs, I feel like giving the CAM the instruction to "stay forward" helps out a lot on creating counterattacks once you've gained possession. It will make him stay up and ready to receive passes. You can swap Klaas-Jan Huntelaar with Stefan Kießling but if you find that both of them are a bit slow, you can easily swap them for Ciro Immobile. As far as my personal preference goes, I like having a pacey ST paired with a slower but better finishing ST. But the duo of Ramos & Immobile have worked really well for me in the past as well.