Well there's lots you can do but first a little diagnosis..
Try turning the headlights on (full-beam or brights or whatever you call it in calif.) and looking at them as you or someone else tries to start the car (or shine them onto something). Do they go dim?
If so, it's probably your battery - did you tighten the connections when you changed it? If the connection is at all loose then not enough current will flow.
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black