Israeli settlements are expanding in the West Bank and destroying the two state solution. Boycott goods and services from Settlements.
Israeli settlements are growing in the West Bank and increasingly destroying any possibility of a two state solution. The areas in white and blue (below) are restricted areas inaccessible to Palestinians. Much of this land is used for military and agricultural purposes by Israel. Israeli settlements are scattered throughout the West Bank and each settlement is connected to another and Israel by roads inaccessible by Palestinians. These roads along with the white areas prevent Palestinians from leaving their own villages because they are surrounded by them. Major Palestinian cities such as Jenin, Nablus, Ramallah, Hebron, Bethleham, Jerusalem (joint), and Jericho are completely severed from each other and only Israelis can travel between them. Palestinian born and raised in these lands are unable to visit holy cites in Bethleham or Jerusalem because they are land-locked into their villages. 

Israeli settlements are growing. Boycott the goods and services produced by their inhabitants to protect yourself from supporting the occupation. 

It is illegal for Israelis to boycott goods and services from settlements. Such actions are prosecutable by law. You living outside of Israel are free to do what you want to uphold justice at least on the bounds of your wallet. 

In a April 2013 Jerusalem Post article: The European Union seeks to correctly label which products are made in Israel and which are made in Israeli settlements:

In a August 2012 Guardian article: South Africa re-labels starts practice to distinguish goods from Israel and Israeli settlements.

Some companies that operate in Israeli Settlements are:     Settlement: Barkan I.Z.   Settlement: Atarot I.Z.   Settlement: Edomim I.Z.

Companies to Avoid

Achva (source) Operates in Barkan
AHAVA Dead Sea Laboratories Ltd. (source) Operates in Mitzpe Shalem
Amgazit (source) Operates in Gush Etzion
Beigel & Beigel (source) Operates in Barkan
Caterpillar Inc. (source) It's equipment is used to destroy Palestinian villages and replaces them with Settlements.
Hewlett-Packard Company
Keter Plastic Ltd. (source) Operates in Barkan
Soda Stream (source) Operates in Edomim
[ - ] jcancellare 1 points,

Might I suggest that you add Walgreens to the list of boycotted companies? They offer very many products of Israeli origin

[ - ] JivanAmara 1 points,

Caterpillar, just because their company's products were chosen to tear down the settlements?  I think that's too excessive to join this Boycott.

[ - ] essem 1 points,
I have an acquaintance who works for caterpillar, he's quite proud of the custom built armoured bulldozers they've been developing specifically for the Israeli settlements for many years. I agree with their boycott.