How do i make my car faster?

I have a 98 Chrysler Sebring with the 2.5L v6 and i was looking of ways to add 25 to 75 HP easily. all i can find is Cold Air Intakes and Chips. i have already ordered a CAI and looking at a Volo performance V12 chip. i have a budget of 500 bucks and would prefer to do all the work myself so the need of special tools is unwanted but if necessary i will rent them. thanks