Basically just soak the terminal ends with the baking soda/water, it will help to eat/clean the corrosian on the terminals. A wire brush does a good job alone.

I had a '91 S-10 Blazer that wouldn't start. Turn the key and everything would come on dim and it wouldn't even crank. I tried jumping it and it made no difference. I banged my head against it for a while (it started fine the night before). Finally, someone suggested cleaning the terminals and it fired on the first try.