Three things I learned as arbitrage and inefficience in stock market here at Brazil was:

1- buy stocks here at Brazil and sell the connected ADR at USA o vice versa

2- watch overseas contracts in BMF (futures ), if there is a a huge number of overseas contracts contracts bovespa will proceed up

3- in case you have two stocks quite correlatated (two banks by way of example) you buy the cheaper. In the future if the other is cheaper you sell the first and use all this cash to buy (I believe you attempt to double you position). Instead of bank profits you attempt to raise shares. Your hope is that if the talk goes from R$30,00 into R$10,00 you've tenfold your amount of stocks. One day both will increase worth at least or too will have the exact same price but you have stocks. The risk is among them broke never return to correlation before you increase your stocks enough to make profits.

So the comparable I will see in Forex are:

for 1- buy spot sell CME futures. So easy that I doubt it functions.

For 2- COT report. Too much lag.

For 3- I do not recall any egy relating to this (increase lots). Here we've swap too. So a notion is increase lot in pairs (possibly two baskets?) Who have positive swap (even though not the objective it is necessary).

Some ideas?

EDIT: just realized that pip worth can be exceedingly important trying this here.