The easiest card to get to start building credit is a basic visa, discover, or mastercard that will likely have a very high interest rate. Just a tip, it is usually a bad idea to get contracts for something you dont already have the equipment to handle. It may not be so in your case, but it will usually be stressful as it stresses you out and puts tension on the client/lco relationship. Go for jobs your outfitted for until you've saved enough to expand/ or built enough credit, as in a 700 score to know you can get good financing.
Also, dont fall into the online credit score trap, they often show your score to be 50 or more points higher than banks and other lenders do. I dont know why this is the case but you'll find it to be true.