If you aren't going to fly 125 hours a year or more, rent. If you want to get your ratings quick and cheap, buy an IFR 150, 152, 172 or Warrior, put the least amount of money down that you can. Don't borrow money for anything else. Partnerships can be great in this instance. Fly your butt off until you have your private, instrument, and 240 hours. Then sell it as quickly as possible. You have to do 10 hours complex for the Commercial rating, and you can start learning the manuevers in your plane. Do the commercial, CFI and CFII as quick as possible. Then, you can get paid to fly and build time while in school. Only then would I consider a commercial Multi Engine add-on, unless you have access to a twin REALLY cheap with attainable insurance.