Do you just have the default personnel? If so, something like this worked well for me:
4-2-3-1
GK on standard/defense
Gibbs(WB-A)-Koscielny(CB-D)-Mertesacker(CB-cover)-Debuchy(WB-A)
Ramsey/Wilshere(B2B)-Arteta(DLP or Anchor, depending on defensive need - Defense)
Cazorla(Winger-A)-Ozil(Trequerista)-Sanchez(Inside Forward-Attack)
Welbeck (Complete Forward)
I was doing this while Theo was injured, but he could slot in in place of Sanchez and you then may move Sanchez up front in place of Welbeck (heard others had good luck with him in that position, personally haven't tried).
Ramsey/Wilshere switch off (since they always get injured) and you also have cover with Rosicky and Ox. Ox also covers the wings (especially right) if needed.
If you need more defensive cover you can replace Ramsey/Wilshere with Flamini (or just change their role/duty) or make one of your fullbacks support oriented (but do so on the side opposite the Inside forward).
I would also at times move Sanchez to the left, still as inside forward, and place Ox or Cazorla on the right. I think Sanchez was more dangerous, attack wise, that way, but he was still good on the right, but more with assists.
I would often place Control, but you may want to start with standard. Play offside trap (unless you are getting beat a lot, but Merty on cover should help there) if you are playing control - if you are playing standard, its up to you.
Fluid since Cazorla, Ozil and Sanchez are individually creative.
Be sure to work ball into box, and play short. I never set 'look for overlap' but have been doing that with a new team (in MLS, for what its worth) and that has been helpful so you may want to try that too.
Best of luck!