They are relentless, especially if you have deer or tall grass around. I battled them last summer and what worked best was clearing brush and laying down permethrin granules in the shady spots. I also fenced the back area to keep deer out. Not perfect, but the numbers dropped big time.
Ticks are tough because they hide in tall grass, brush, and shady spots. Keep the yard trimmed, remove leaf piles, and treat the edges, sometimes it takes repeated treatments or even calling a pro to knock them back