Scotland is quite manageable to travel around on your own, and using public transportation.  Frequent buses going to every corner of the country allow you to access the lesser discovered areas, while trains and larger bus companies will take you to the main cities and tourist destinations.  Your other option would be to rent a car, and brave brave driving on the left!

By Air

If you're looking for how to reach Scotland, your best choices will be by arriving in either Edinburgh Airport, or Glasgow Airport.  However, you may also find international flights into Aberdeen Airport, and Glasgow Prestwick Airport. Inverness Airport has recently added an Inverness - Dusseldorf route, but otherwise you are likely to have to arrive in Inverness via London, or another British city.

By Train 

Seeing Scotland by rail is one of the most enjoyable ways to view the countryside. You can search Scot Rail for Scotland rail connections, or National Express for rail connections between England and Scotland.  There are also train passes available from Rail Europe in a variety of different types, so check for what works best for you and your travel itinerary. 

By Bus 

Traveling by bus is likely your cheapest option.  Megabus and City Link are the main companies for express travel from city to city, however Stagecoach may also be useful as well, if you're trying to get to smaller towns and areas. City Link also offer explorer passes if you intend to do a lot of travel within Scotland.