For temperature you can go lower and lower until the extruder motor starts to skip a little, and then go back up 5-10c.  Sometimes you can tell if you are approaching the lower limit on temperature if teeth marks from the filament gear remain in the extruded filament.

I'm still learning tricks and techniques, but I am curious about proper temperature settings. I did a quick google search on how to tell if you're using the right temperatures, and didn't find anything. So, now I'm here! I've always had a problem with the filament leaking out while heating up before a print. Not sure if that's something that happens normally, or if that means my temperature is too high. Prints come out fine, but on some I get a little stringage. If I'm doing a single item with not too much variation, prints come out great.

I read on SainSmart's amazon listing that their melting temp is lower than others, so I've been trying lower temperatures for the first time. I'm making a Tardis ring topper with this new blue filament from SainSmart, but when I make more than one, it gets a little stringy.

Single Tardis topper printed on high at 100% infill, 1 shell, .10 mm layer height, 220 C temperature, 80 mm/s while extruding, and 150 mm/s while traveling.

I was happy with the results, although in the high quality picture you can see the flaws. So I went and made a group of 5 to print together. This was where the problems came about. I had to relevel the build plate because it was a bit uneven from a different print we were messing with.

I printed the second with the same settings except I went to a temperature of 215 C, trying to make sure there was no stringing. Pictures are attached.

Just looking to see if anyone has some tricks, ideas, or anything to help me out. Anything would be appreciated!