Stay well away from them.
End of story!
I'm with newcrew. In my experience, it isn't the end of the story at all. If you take the tropics into consideration, there probably wouldn't be many viable airline routes in the wet season!
The way I see it, for an approach, you may well find the area covered with scattered CBs. If the airport is clear I don't see a problem with continuing the approach if you can remain clear of the weather and preferably upwind. Chances are the controller will be under a lot of pressure and you'll be vectored into the weather, so R/T traffic will be high with requests for deviations from track and late clearances can be expected. I have once heard the poor controller melt down too, obviously then you do what you have to to stay out of trouble.
I have often found CBs down the final approach track or crossing it. Quite often a change of runway is not possible or just plain refused. If faced with that you have to assess if you can parallel the track and/or get back on final before MSA and establish a stabilised approach, just be prepared to break off the approach as soon as you have doubts about achieving that and think well ahead of time in what direction you will break off to too!
Obviously the approach cannot be continued if there is TS in or around the airfield or anything where the required missed approach path will take you. Request an alternate missed approach early if necessary with consideration for how busy R/T is already.
Also, it is handy to have the confidence to be able to separate TCU from CB. TCU will be a bit bumpy but not problematic. It is also helpful to be able to differentiate radar rain returns from convective cells too. Innocent rain is flyable despite being painted red.
If you suspect that a hold maybe a good idea, try to request it early before the approach. Holding above MSA on final maybe an option too.
Keep a very sharp listen out for other traffic, keep each other informed of where the traffic is and what they are requesting, use the TCAS display with the above/below option if available.
During late final to landing, be alert for windshear, don't rely on reactive or predictive systems, but keep in mind the annunciated criteria for a windshear escape manoeuvre - its in the QRH. Obviously, with potentially challenging runway conditions a deep landing should probably be baulked.
With regards to fuel, clearly taking minimum flight plan fuel with the possibility of weather would be highly questionable. I'd probably be looking for an extra 30 mins plus, plus anything else that I usually take into consideration. Sometimes though, you have to make a decision to divert or commit, that decision needs to take into account your current position as you maybe holding away from the field significantly increasing track miles to the diversion field, so what you have entered in the FMC during preflight maybe misleading.