A few ideas;
1. Replace the hinges with security hinges than either have the pins welded in, bradded over on the end or have some kind of hidden retainer that can only be remove with the door open;
2. Replace the screws with ones that go clear through the casing into the 2x4 or 2x6 framing on both the hinges and the striker plate;
3. Install one of those reinforcement plates around your knob/deadbolt area that reinforce the door and also cover up the striker and deadbolt to prevent tampering with them;
4. Remember that any of this doesn't much good with sheet rock only walls or hollow core interior doors that are easy to break through so a secure door is only a deterent if the walls are flimsy.
Also, something that looks secure is usually as important as the actual security itself. Another thing to remember is obvious security of unusual degrees is a flag that you have something to protect, so stealth and reasonable security is a great plan.