Scotland hasn’t had a foreign policy since the Act of Union in 1707, and to some extent not since the Unions of the Crowns in 1603. It is therefore interesting to have a look at what kind of international outlook an independent Scotland is likely to have.
First of all, every country is to a large extent focused on its neighbours. Whereas from London the neighbours listed by a combination of closeness and size are France, Ireland, Netherlands, Germany, Belgium, Spain, Denmark, Norway and Iceland, the list of the neighbours as seen from Edinburgh goes something like England, Ireland, Norway, Denmark, Iceland, Germany, France, Netherlands and Belgium. In other words, Scotland is likely to pay much more attention to especially Norway, Denmark and Iceland than the UK; on the other hand, Scotland will probably not be as preoccupied with France, although I’d expect the relationship to be very friendly, perhaps even to some extent reviving the Auld Alliance.
Secondly, Scotland is likely to have a very close relationship to Canada, the US and other countries with significant numbers of citizens of Scottish descent. According to Wikipedia, there are almost 10m Americans and almost 5m Canadians of Scottish descent, which is likely to make these countries close partners. Other countries with significant numbers include Australia (1.5m) and Argentina (100k).
Last but not least, the UK’s foreign policy is to a very large degree defined by be effects of the British Empire. Scotland would be much less tainted by this (although of course Scots played a full part in the Empire). So whereas the UK has a difficult relationship with Argentina because of the Falklands and with Spain because of Gibraltar, there is no reason why an independent Scotland shouldn’t enjoy cordial relations with both Argentina and Spain. Scotland would also be a normal member of the UN without a veto in the Security Council and without nuclear weapons, so there would be less of an incentive to formulate a policy vis-à-vis all the countries of the World.
To sum up, I expect Scotland’s foreign policy to be focused on Scandinavia and North America, and to be friendlier and less global than the UK’s.