The type and strength of your fishing line will depend on the type of fishing and where you are fishing.
Clear Water Finesse Fishing
If you are fishing clear water, the key to getting more bites is down-sizing your line. 6 pound line is ideal for getting more bites, but strong enough to avoid snapping your line if you know what you’re doing. Many anglers will use 8 pound line to avoid snapping the line with bigger fish, but you can definitely get away with 6 pound line if you use light action rods and are careful when bringing the fish in. Fluorocarbon line is very popular in clear water because it is very difficult to see that line under water. Spool your whole reel, half your reel or just add fluorocarbon as a leader. Just make sure you’re using it to get more bites.
When fishing murkier water, you can go heavier if you want with your fishing line. For most situations, 10 pound line will work well whether you are casting crankbaits or fishing with soft plastics. 8 to 12 pound test line is a good range. You usually don’t have to go real heavy because you won’t be fishing around as much heavy cover as you do when targeting largemouth bass. You’ll usually be in open water over and around rocks when fishing for smallmouth bass.
Northern pike make smallmouth bass fishing a little difficult at times. When fishing good lakes that have northern pike and smallmouth bass in them, your best bet is to add a 30 to 40 pound fluorocarbon leader to your fishing line to avoid bite-offs. You may catch less smallmouth bass, but you’ll avoid the bite-offs. Some anglers go a little heavier, but make sure to fish more worm and crayfish baits that are finesse-sized. This keeps the bigger pike from biting and you can usually bring the number of bite-offs way down this way, especially when going up to 12 or 14 pound test line.