Here are a few ways:
The A+B Putty method
Stretched sprue ( I also like to use the very fine EverGreen rod for uniformity) hit heahily with liquid cement and prdded with a dental pick.
PE - Was pretty nice, but was a gift from Mark at On the Mark, but I normally wouldn't spend that kind of money on it.
And for some welds, especially those capped with low hydrogen rods, (nice and smooth with no visible "row of dimes) I use a sharp needle or piece os styrene and CA.