A good 25, 40 or 60 watt soldering iron with a moderately large tip should work well. Get it up to temp, first, and use a substantial tip to convey lots of heat quickly. A very narrow pointed tip will take longer to heat the item.
If you want a good soldering station, consider Weller products for more than $100. Here is why: Cheaper stations stay hot all the time. If you leave them on for a long time, the tips oxidize and fail quickly. My Weller WE1010 costs $100 and has 1) a n accurate digital temperature displays, 2) sufficient wattage to heat the tip quickly and supply more heat if the component needs it, 3) It automatically cools down after awhile, to save the tip from dying young, 4) it is more durable and long lasting than the several Chinese stations I have used, 6) Weller tips are better, longer lasting than Hakko tips typically used with Chinese stations, and 7) the base controller seems, to me, more durable and robust. If you save money and get an iron or station that does not automatically cool down after a time, then turn it down yourself if there is an extended period between soldering components during a longer project.
Get some extra liquid and paste flux and use it whenever you encounter a stubborn or difficult joint. Do not leave your soldering iron or station on longer than necessary as it quickly takes a toll on the tip and a good, clean tip is essential to quick and effective heat transfer. Tin the tip before and after each session to prepare it for the current job and coat it between jobs. More heat than specified to melt the solder is better than less or exactly what is specified. You have to heat the component as well as melt the solder. If the solder is specified for, say, 400 degrees, heat your iron to 450 -480 degrees - but not much more, as overheating can wreck the solder and over cook it (so to speak) - you want enough, but not too much, or the solder does not flow as it should. Too little heat will heat the component too long before the solder flows. And, once it flows, remove the iron and let it cool - over heating is contraindicated. ALSO, tin all wire and many component leads with solder before you attempting to solder the leads to a component or a component or wire to a PCB. Sometimes it helps to re-tin a previously soldered or tinned lead or component. Fresh solder seems to revive old solder, such as soldering a new cable to an old, used connector. It is all about clean heat transfer. You want lots of heat to transfer very quickly, and a larger, thicker tip and enough heat will solder leads to your condenser elements with no issues.
YES YOU NEED A HEAT SINK, if only to be safe and not sorry. If you solder quickly and with sufficient heat, you will make a quick and secure connection without overheating the component. Use a heat sink to be sure - even if you improvise with aluminum foil, tweezers, pliers, metal vice, or other heat sucking material. Anything will be better than nothing.
And that is just MY take ... you mileage may differ. I learned to solder from guys making prototype circuits for nuclear weapons for the Defense Dept and RF gear for NASA. Others may have a different take, so read all you can on the web before proceeding - and do not be afraid to dismantle and reassemble a couple of old circuit boards for practice. You will learn the most by practicing what you read. Good luck. James - K8JHR
