1. Use a soldering iron that can hit 400, and use a needle tip 2. Use leaded solder - lead-free is a pain. If you're not doing this for hours every day, even without ventilation, you'll be fine. 3. Heat the pads you're soldering to, not the solder. I used to tell kids to hold the iron to the pad for a count of three, then feed the solder in. 4. Two additional tools I find helpful - a solder sucker and copper wick.
I have to disagree with that. Almost every time I've been called in to rescue a frustrated novice at the soldering bench (which has happened a lot), I've found them using the thinnest tip they could find with the temperature cranked to 400°C or higher because nothing was melting. It's fine to have an iron that can exceed 400°C (and I can't think of any I've used that couldn't), but that capability should be rarely used.
A heavier tip -- generally the heaviest that will fit between obstacles on the board -- at a lower temperature is much more forgiving.
The small tip has little heat capacity, significant resistance between the thermal reservoir (the heavy body of the tip) and the contact point, and usually very little contact area with the work. That makes the temperature at the joint highly sensitive to tip position, surface contamination, and copper geometry on the PCB. A thick trace or ground plane connection sinks heat from the joint so well that it will never melt, but a small pad on a thin signal trace will quickly get hot enough to detach the pad. Gunk on the board or oxidation of the tip adds more variability. And the high idle temperature makes for fast oxidation of the solder coat on the tip and then the plating, which creates more problems and frustration when you're new and don't recognize those symptoms.
A fat tip provides a large thermal reservoir right at the contact point and usually creates a larger contact area that's less disturbed by a bit of contamination. The much lower thermal resistance brings the joint temperature closer to the iron's thermostat setting, allowing you to keep that setting lower -- I'll go as low as 300°C for SnPb on a not-too-heavily-coppered board, maybe up to 350°C for lead-free. That gives you consistent heating of a wide range of targets and is much less likely to lift pads even with the long dwell times that often happen while a novice is learning. At the low end, it slows tip oxidation enough to make it almost a non-issue. And less flux charring means less gunk on the board to interfere with the next joint.
Predictability makes the whole learning process much smoother, and running small tips at high temperatures creates all sorts of issues that are hard to see or understand until you've got some experience behind you. When in doubt, use more copper before using higher temperature.