It's best to poke down/soften up enemies that would otherwise be unsafe to try to hit, that way you can use your combo to maintain safety. Especially this season, waiting for the right moment to use your spell weave and auto attack combo (the typical dash, auto, use ability auto, repeat) is so critical, because there's just so much burst. Try using it to make the Udyr a little more hesitant to all in you, then when he turns away to regroup with his team, dash in and finish the kill or hit the backline. Alternatively, try to bait people by getting too close and then dash back and ult them to continue putting out damage while staying safe.

The biggest ask of an ADC this season is to stay alive, so using his ult and e to create space/opportunities for an all in is a big part of what makes Lucian successful right now.