Best practice to build a ligature?

Alexander Stetsiuk

Create a ligature glyph
Livory

Two or more glyphs combined into one
FF Super Grotesk

Kent Lew

One piece is more effective if the combination has qualities that would be impractical to achieve with two separate glyphs — like the rounding of the corners of the counters in the first example.

Two separate glyphs may be a more practical approach if one or the other can be reused with multiple partners — e.g., OC, OG OO, OQ in your second example.

Both approaches have advantages and disadvantages. I do not think there is a single “best practice.”

Craig Eliason

The fit of the second approach may be compromised if tracking is applied.