Hello /r/AskHistorians, for part of my college course I need to write a 4000 word Extended Essay so I chose to write it on the Punic Wars. I know this isn't a subreddit to be asking for help on homework/college work but I'm here to ask help on finding reliable primary and secondary sources on Punic Wars. I have already found a few myself (books/accounts by Polybius and Appian).
I would be very grateful if someone would be able to direct me to any more sources on the Punic Wars and/or if they are knowledgeable on said Wars what would be useful to write about.
I'm going to let you swim regarding the sources, because I believe looking for and finding sources is part of what you should learn from such an assignment. If you put in a little bit of effort it shouldn't be too hard, since you're already at this subreddit (browse a bit).
One thing to realise is that the three Punic Wars are three completely different beasts, so to speak. In the First an emerging empire clashed with an established empire, in the Second two empires went for each other's throats, in the Third a 'world' empire squashed a fallen empire like a fly. Do you want to pick a common theme in all three of these wars, or do you want to pick a war and look at that one in a bit more detail? Both options are viable, though making a comparison between the wars is complicated by the different circumstances and by a varying quality of sources.
You mention Carthaginian mistakes in the title; there certainly are examples of decisions/actions which might be called mistakes. If you are going to take this approach, do realise that we now have more information than people had at the time they had to make a decision. They may have taken a completely sensible decision which turned out to be a mistake in hindsight. Only seldom do people purposely set out to do something stupid.
((As an aside, I will say this now: if and when you are collecting these mistakes, please do not call Hannibal's decision not to attack Rome directly a mistake. Hannibal relied heavily on favourable terrain and ingenious tactics to win his battles, those advantages would be lost in a siege. Furthermore, he needed to stay on the move in order to supply his army; he had no proper supply lines and no way to feed his army if they stayed in one spot - such as in a siege - too long.))
Questions like "What are interesting [persons, events or sources]" are always difficult to answer (what might be interesting to me might not be interesting to you). If you have any specific questions (perhaps after some initial research), I'll be happy to have a look and try to answer them.