Spring temperatures should be categorized as from about 50 degrees to about 60 degrees. During this time the bass are generally in the pre-spawn or spawning stage. This is the time of year when they are close to or on the nest or bed. There has been allot of controversy as to whether or not people should fish for spawning bass or not. Research has shown that if they are landed fairly quickly and released immediately they will return back to the bed. But if you feel that this is still not fair you have every right not to fish for them.
During this time of year almost every lure imaginable works. Topwater is probably the most productive lure for this particular time though. Lure depths are usually in the 1 to 5 foot range. But this depends on where you are fishing and current water conditions. You might have to fish as deep as 10 to 15 feet if that is considered shallow on your lake. Floating Rapala's or similar types are usually fantastic as are buzzbaits, soft jerk baits, worms and probably even the Banjo Minnow. All coves and inlets should be thoroughly checked out and all points leading into the coves. The best thing to remember about this time of year that even though lure speeds are generally faster, if what you are using is not producing slow down your retrieve or change your presentation.
Remember how the Northern areas warmed up first earlier? Well now those are still the best areas to fish now and those fish will also be the first to be on the bed. This is also the best time of year for that lunker of a lifetime so be prepared. Keep your tackle in the best condition possible.
When you are fishing topwater always keep a second rod handy with a worm or a crankbait tied on. Most of the time if you miss a strike on topwater and throw back right away with a worm or burn a crankbait through the same area you will connect 90% of the time.
For a good book on the basics of Smallmouth Fishing try the above book by one of the nation's best Smallie Fisherman, Al Linder.