Checklist
1) Be clear about what you are buying and honest with yourself about why you are doing it. Identify any overlaps and inbuilt conflicts between the two organisations and be prepared to deal with them from day one. Keep emotion out of your decision-making process, but recognise that acquisitions should never be just about the bottom line.
2) Avoid alienating your new colleagues. You are your company's standard bearer and as such, you need to be visible and accessible and you need to win their respect. You must also treat them with respect and most importantly that means talking to them.
3) Communicate. Telling compelling stories is part and parcel of successful leadership and you need to explain the reasons for the acquisition, your vision for the future and how you expect your new colleagues to contribute to this until they beg you to stop. Use an idiom they understand - and be ready to engage in some robust if not downright hostile debates. They are only human, probably a little scared and certainly feeling insecure.
4) Be decisive. Indecision is 90% of stress- and that holds true for you and for your nw colleagues. It is vital to identify, retain and motivate key new members of staff as soon as possble so that everybody can move forward. Inevitably that will mean disappointing and probably losing some people whose career expectations have been thwarted, but that's life.
5) Build a common culture. Probably the hardest task of all, but if you can identify common values and terms of reference, then you will be half way there.