On education: I recommend reaching out to a Baltimore tax sale attorney. Some have slide decks available with really good info on the tax sale process for Maryland. They do this because they want your business for the legal work on the tax sale foreclosures.
Budget: With $5,000 you could definitely buy some liens. The great thing about the City tax lien auctioneer is that their software automatically withdraws your bids once you reach your budget. So you could place lowball bids on dozens of liens, and hope to get lucky with a couple. And after your budget is exhausted your remaining bids would automatically be withdrawn.
The tax lien jedi @Ned Carey once taught me that there are generally two types of tax lien investors: people who want properties and people who want interest. It sounds like you want interest. So keep in mind that property owners can redeem at any time. It's very possible you could buy $5k in liens and not even make enough interest to make up for the $100 bidder registration fee.
Finally: tax lien investing is NOT risk free. You are buying the right to foreclose on a property 1-2 years in the future, regardless of its condition. Last year I got a killer deal on a lien...looked great...then it burned up in a fire.
And earlier this month I had another owned property burn up in West Baltimore..see photo below. (@Russell Brazil is going to laugh because 3 years ago when I marketed it for sale, I wrote "some components still salvageable"...well, not anymore Russell.) So tax lien investing is anything but risk free!