First, many thanks to all for enlightening comments that have been very helpful to me. I’ve been learning fiddle (coming from mandolin) for almost a year and am making slow but steady and encouraging progress. 

My question is about left hand fingering for successive half-steps, especially at speed. For example, the pickup notes for  “East Tennessee Blues” are E - F - #F - G on the E string. (Tablature would be 0 - 1- 2 - 3.)

A quick and dirty approach would be to use the first finger to slide from F to #F but I’d like to be able to play those notes distinctly. I could play F, #F and G with fingers 1, 2 and 3, but that feels oddly out of position as I play the succeeding notes. Normally I’d be playing the G with finger 2. 

I have encountered the same issue with other songs and other positions on other strings. 

Maybe I just need to suck it up and accept the awkwardness and learn to adjust my patterns and intonation -- just another one of the myriad challenges of the fiddle...

I’ll appreciate any advice,

Strabo