My Van sometime starts and sometime don't

Dodge Caravan 1993. 210,000 miles on it.

Is/Was working fine. 2 days ago did’nt start, 2 click nothing.Lights were dim, horn barely working. Jumped started it with my friends car. Was fine till yesterday. Again same problem. Thought battery might be the problem, Got a new one. Still won’t start. Left it for a few hours and gave it try this morning, the engine turned without any hitch. Turned it off and started again a few times. All seems to be well now. What is wrong ?What might be the problem? Would like you guys to help me out.

Clean the battery connections using a battery post cleaning brush. If that doesn’t help then make sure the power panel under the hood is getting proper voltage along with checking the battery to chassis grounding.