1. the first batch of numbers eg. 10.x.x.x , i correspond to the country they are in (for example 10 is U.S., 11 is Mexico, 12 Brazil, you get the idea).

2. the second batch of numbers, eg. x.122.x.x , i correspond to the office number in that particular country for example in x city they get 122, y city 123.

3. the third batch, eg. x.x.1.x is internal and states the topographical level of the offices network, for example a top level VPN would mostly have 1 in there second level a 2, this is more internal than external it helps manage users inside that branch.

4. and finally we get to the internal ip scheme which i use the last batch. this is where i like to set up statics. aka 1-9(or 19, depending on devices) is reserved for devices such as NAS, AP's, etc. Servers i usually reserve 20-49, 50-199 are my static clients, all the computers we have authorized on the network and have access to all servers and file systems. And finally i reserve 200-254 for the dynamic clients which are isolated from the network and can only access the internet, such as special privilege guests(or sometimes the idiot walking outside the office).

Thats it, thats all, pretty simple stuff, all it takes is a little bit of planning and you'll have a global network up and running efficiently!