At smaller stakes you should primarily focus on widening your 3-bet value range since you'll get weak opponents calling with worse, you'll have initiative post flop against players who will play a lot of hit/fold poker. Against these opponents you can win a ton of pots by just c-betting post flop. You can work on smaller sized 3-bets in position with a ton of hands, AJ,KQ,ATs, etc... because you'll get calls from worse, A9s, KJ, TQ, etc...
If you do start polarizing your ranges, it's more profitable to 3-bet w/ hands that can out flop your opponents 3-bet calling range instead of suited connectors etc. That's not to say you should never 3-bet SC's, but flopping 2 pair+ with these hands is rare, and you can easily flop second best hands a lot where you'll lose at bet or two post flop. So something like K9s/A4s is much more profitable because your opponents 3-bet calling range will include a lot of hands you can out flop TT/JJ and QQ in some cases. It's much easier to get to showdown, and you also cut out some dominated comb ranges when you do this.
Work on this primarily in position first, and then mix in some OOP ranges.