Yes, a speed secondary is generally a must for all characters. It also may be helpful to just read through a character’s abilities to see what other secondaries may be helpful. For instance, some abilities may say things like, “gain a bonus based off 10% of max protection.” That would then let you know you would like to have some protection stats on the mods. The source I use for mod help is swgoh.gg. Just google “best mods…” for whoever you’re working on, and click the result from swgoh.gg. It shows what top players use on the characters, as well as a few other helpful things. That’s my best advice, but perhaps someone else will have other tips.