@Ernie V. Hello! Welcome to BP, I'll tell you what you'll hear from everyone, you've come to the right place here because there is an absolute wealth of great information here, far, far more than could ever fit in any book or even on a set of DVD's or whatever other media! Plus, unlike nearly every other website that claims to be for RE investors, this one isn't just a little bit of info that's meant to lure you in so they can then put the hard sell on you to buy some "educational materials" at some ridiculous price! They do sell a few things I suppose, like the book on flipping houses, which I bought a copy of myself even though I've been flipping houses since 2004 or so and I still learned from it! That book is $30 or something around there, much better than the $2000 or $10,000 or whatever crazy price other people are charging for their "can't miss" programs!
Anyway, to answer your question (or attempt to) about the "best" areas of Milwaukee to invest in, quite honestly you could really make a case for ANY area being the best area! What I'm really saying is, you need to sit down and really think about and analyze what your goals are-both short and long term, what you have as far as money to invest-either cash on hand or what you're able to borrow from a bank, relative, private money lender, whoever. Also, you need to decide what level of involvement in this you're looking to provide, is this going to be your new full time career or is it something you'll have to manage to do outside of the time required for a full time job, or maybe somewhere in between. I'm sure I could think of more criteria for you to consider, but those three things-your goals, what you have to invest and how much time you can spend on it are a good start.
From there, first off, are you just talking about the city of Milwaukee itself or the entire metro area (a big area to cover) or part of the metro area or ????? Just for this example, lets say you're interested in all of Milwaukee County and eastern Waukesha County, which is still a good sized area but fairly reasonable. Now, what are you looking for out of these investments? Probably the two big areas or RE investing these days are rehabbing/flipping houses and buy and hold (being a landlord). Again, for my example, lets say you're looking to buy and hold. Then it comes to your short and long term goals, are you looking for big time monthly cash flow, long term appreciation of the value of the properties, maybe a combination of the two? If you're looking ONLY for maximum cash flow and really don't care about appreciation, (you'll certainly take it if it comes, but you're not counting on anything big) then quite honestly, some of the "rough" areas of the city of Milwaukee are where you should start looking. If you're new in town, just go to the Milwaukee Journal website and look at their interactive "crime map". You'll see that the vast majority of murders are all clustered in mainly one or two general areas-guess what-those are also usually the best areas for pure cash flow and a good number of investors make great money in those areas! You'll also see, looking at the for sale listings, that you can buy properites-single fams, duplexes, multis-for some incredibly low prices in those areas. Of course, they come with their drawbacks too, how interested are you in spending time in areas where murders are fairly common? Again, some investors don't mind at all and they can do very well in those areas, in fact they'd probably tell you those areas are the best to invest in, because compared to buying in higher priced areas, they're still getting decent rents and they paid a fraction of what you'd have to pay to buy in other areas, for not a whole lot more rent!
Moving on from there, as the neighborhoods get safer as far as crime rates go, the prices to buy will go up, as well as the rents, but the rents usually don't go up proportionally as much as the purchase prices, so your % return gets lower and lower. Taking it to an extreme, you could buy a house in Elm Grove and pay a LOT of money to buy it and then rent it out but between your interest, taxes, maintenance, etc you might not be cash flowing much at all! The flip side is that while the super cash flow properties in the high crime areas pay out every month, the long term appreciation may not be much at all, while the Elm Grove home might end up going up in value enough to retire on! (certainly not guaranteed though!) Between these two extremes, are a lot of areas that are safe areas but nothing fancy, where you can buy in for a reasonable amount and get good rents, so you'll have some cash flow as well as a good shot at some long term appreciation.
Lastly, for your condo question. I've bought a bunch of stuff through the Milwaukee and Waukesha Cty sheriff's auctions and condos are a crap shoot in my opinion, but with enough research you certainly can make money there as well. There are a bunch of low end condo complexes, many on the NW side of Milwaukee where they have units going through the auction constantly and since they're usually bought back by the bank, they're then listed on the mls, many for $30k or well under that. I don't know too much about those condos, not my "cup of tea" but I suppose you could buy one and rent it out and cash flow on it. On the other hand, there's been a boom over the last 15 or 20 years of new condos downtown and in the 3rd Ward, which are generally all pretty pricey, usually starting around $200k for a 1bed/1bath tiny unit and going up into the multi-millions in certain spots like University Club Tower where one 9000+ sq foot unit that covers an entire floor on maybe the 35th floor is appraised by the city at $13 MILLION!!!! If you can find a steal on a downtown or 3rd Ward condo and either want to flip it or buy and hold, you could also do quite well. BUT!!!!!! Before you consider buying ANY condo, get to know top to bottom what banks are looking for as far as the financial health of the condo associations!!! Banks learned the hard way over the last 5+ years that writing mortgages on condos in complexes where the condo associations are poorly run, have little or no reserves, or whatever other issues can lead to disaster such as when the whole place needs a new roof badly and there's nowhere near enough in the reserves for a new roof, which of course will cost BIG bucks for a giant condo building. How do the condos get a new roof then-like when its so bad that its leaking all over the place and destroying the entire building and the lowest estimate is $300k??? If there's 30 units in that building, then the only answer is to send each unit a bill for $10k!!! So, definitely do lots of research on that whole part of buying any condo!!!