good advice above:
30w iron for small wires only
60w iron for most everything else
ALWAYS USE FLUX, I like the gel/paste type but liquid ok too, it makes the solder flow into the parts way better.
HEAT THE WORK, once hot enough the solder will flow right into everything but USE FLUX
Additionally remember rosin-core solder for most hobby uses (and all electrical type connections) as acid-core is for plumbing with copper pipes and for structural things.
I spent the first 10 yrs of my soldering life either not getting the heat where I needed it or trying to do a solder connection without flux, either omission will give you fits. Best of luck, your life is about to get better
One more thing, if an iron can't get the heat into the parts fast enough then consider a small butane torch for your heating tool, works good on bigger pieces such as a 4ga 12v wire getting soldered into a large metal terminal that attaches to 12v car batt...