What advice would you give IT leaders looking at outsourcing?

Make sure your house is in order! If you don't have a good handle on what you have, in terms of systems (people, process, technology), you are not likely to be successful in outsourcing. Do the due diligence. Communicate your expectations upfront and clearly. Remember that you can't outsource accountability.

Look at the TCO on a multiple-year span. Often, the desire to outsource is to cut costs; while that might be a quick win, outsourced teams are often not as efficient and customer-focused, so they tend to cost more. Your SLAs might decrease, customer satisfaction might be reduced. You might get direct monetary savings, but the total cost might be higher.

It depends on what team/function you are looking to outsource.
It also depends if you outsource in-country vs out-of-country. You can get cheaper labour in many out-of-country companies but be ready to potentially have to compromise on work ethics, quality, culture and customer satisfaction. If you have a local team that is your outsourcing that works in the same area and same time zone, you tend to have better customer support.
If you are outsourcing for a very niche or highly skilled position and the outsourcing is more project-based, then location/culture/time zone might not be much of an issue.

Outsourcing always comes with a pain, whether you're doing it on location or off location. The hybrid model always works, from what I have seen. When I moved a lot of work from the US to India for a large Fortune 50 company, the biggest challenge was managing people in areas where they didn't want to let go of legacy technology and processes. But in time, we were able to manage it and create significant efficiencies for the organization.

What worked best for me was having individuals who were foreign nationals but had some experience in either Europe or North America. Those were the people that I found the easiest to work with, because they had developed this hybrid mentality of what was acceptable in terms of their training, and what was acceptable in terms of North American headquartered companies.

I created pods of folks from Eastern Europe, Asia and North America, and figured out how to make them all play nice together in the same sandbox with the business. I allowed them to live their true lives, they got along famously and they were outperforming in the long run. It just takes a lot of time and effort.

You have to take the cultural differences into account. One key example is, if somebody says "yes" to you, are they actually saying, "Yes, I agree with you"? Or are they saying, "Yes, I've heard you"? That's one you trip over all the time.