I have run several poker leagues as previously stated. As long as you have a strict set of rules you should have no problems.
There are many things to consider the first of which is
where. As you say - it must be somewhere where there are no restrictions on US and you should also consider Netherlands.
Also
when - what is the best day for anyone who is interested.
Names and numbers - you would need to know names on here and poker names along with the number of players who want to play. You also need to decide whether you would let anyone join in the league after it is underway - this will become one of the rules.
Buy in - best to stick to one buy in that ALL are happy with so you probably need to ask anyone interested what they are prepared to pay on the buy-in.
Number of games How many games would you want to play for the entire league season. I found that 12 games was in fact sufficient.
Points structure - What would your points structure be i.e. points for finishing 1st, 2nd, 3rd etc. Would there be any bonus/bounty points - how would you organise these bonus or bounty points.
Scoring - using a spreadsheet to do the scoring is the easiest I found (excel) and post the results each week in a timely manner.
And finally -
a very clear set of rules that everyone can understand.
The other thing that is most important is if you decide to have bounty points. An example of bounty points that were very successful to begin with was the top 4 of the previous weeks results had bounty points on their heads. However - a word of warning on bounty points - it did result in some players targetting the players with bounty points on their heads and made the game quite uncomfortable on occasion.
Hope this is of some use to show that there is a fair bit involved in setting it up. The scoring part is easyish providing there is only one person doing it and the results are posted each week so players can check they have been given the right amount of points.