baltimore tax / water liens - SHOULD I BID OR OTC?

[Kenda Bell]

Hi !! I am new here and a newbie to real estate. i wanted to know for newbie with a little bit of money (1k - 2k) , which would be the better option bidding online OR waiting & doing the OTC. I concern is that I may get outbid during bidding OR get a junk proper if I do OTC. 

Also, do I need the bid price upon winning in certified check OR do I just pay the tax amount & pay the bid amount if the property is not redeemed by the owner?

Thanks!!