Integration integration and integration. The key to a successful deal and rightly focussed on as a must. 

However I would add a few others:

1 How and who does the due diligence to set the tone for the integratio. 

Using in-house resources helps with integration but also utilising external support is important too.  Ideally the buyer should dictate the due diligence process rather than the other way round.  This means it should not be the seller and seller's advisers who decide what is  'due diligenced',  nor should the buyer default to what is the 'norm' from external advisers.  Don't be scared to shout out. 

2 Access to management - while often resisted by sellers, management meetings, even if policed by sell0side advisers, are key.  Presentations are important but the Q and A is where the real sense of the target operations comes from.  Don't be afraid to ask for follow-up management meetings.  Not all buyers invite their external legal adviser to these meetings.  If you want the most out of them, invite as a 'listen only' participant.  

3 Data rooms - redaction frustrates all buyers.  Don't accept too much redaction and look at ways to get more information, for example via clean rooms with limited access. Once unredacted later in the process insist on time to review rather than getting rushed in a timetable.

4 Talk to peers- peers will share war stories.  If they are genuine peers their experiences should resonate and maybe even ask them to buddy up with you on the deal journey.

5 Time management - if you are short of time or planning a vacation, delay the process.   You must reserve enough time to do the deal properly.   Don't do the deal when you know you are busy.

6 Plan ahead -  if you are thinking about a deal get all internal and external people lined up early and set aside a day to meet the entire team. Emails, Skype and calls are all fine but a physical initial meeting makes a massive difference in terms of team building.

7 Set review days - once you are in a deal you can get carried away.  Set days aside to review what you now know and whether the deal still makes sense.  Don't resist walking away or resetting the bar as events change or knowledge is gained.  Ask for genuine input from your deal team. 

8 Incentivisation - plan how you are going to keep the talent you are acquiring.   This should not be an afterthought.   It should be fixed even before you start the deal. 

9 Talk to the supply chain - often an NDA stops you talking to the target's supply chain but you can use advisers to study the market or talk generally about service.  To get round an NDA restriction why not do the market research pre-deal?

10 Learn and remember - hopefully you will be doing many deals. Remember what went well and what didn't, and force change for the next deal.