Whenever battling multiple foes make a point of not getting surrounded, if possible try and take them out with projectile weapons first as long range weapons can cause hassle.
Health Drinks
Keep an eye out for Spider power-ups that are scattered around the city as these will give you more cash to spend on health drinks.
Money for black suit
First, get an empty mastercard. then go to itunes and log out of your account. create a new one. Fill everything out and when you get to the payment, click mastercard and fill out the information for that. when your finished, you have money for itunes. Which you can use to get the black suit.