The question is a bit broad, kinda like "I'd like to buy a car. What's a good one ?"
Missing are some details such as
A) how liquid does this investment have to be ie how long can it be tied up ?
B) are you looking for regular cash-flow or tax preferred and tax deferred lump sum, accrued or equity gain at the end ?
C) are you willing to potentially lose more than you invest, ie personally guarantee a loan/mortgage as well ?
D) are you ok to lend to or invest into a development deal, or just into an existing real estate asset ?
E) what kind of loss of capital can you tolerate ?
F) can the asset be in a small town, or only in larger cities ?
G) what kind of return would you find acceptable, and what would you find ecstatic ?
H) if lending, must it be in first position, or is second or third position ok ? What LTV ?
I) are you prepared to buy the asset and deal with it if you have to foreclose on the asset ?
J) what kind of ongoing involvement after the cheque has been written would you prefer ? None ? Little ? Be consulted ? Be really active ?
K) are you an accredited investor, ie financial assets over $1M, total assets over $5M or income over $200,000 ?
L) are there certain asset classes you'd never invest in ? Say hotels, foreign markets, industrial, mobile home parks, land development, contaminated land, grow ops or condos. If not, why not ?
M) are there certain asset classes you'd prefer? Why ?
N) Can your investment be one of several into the asset or does it have to be the sole investment ? Why ?
O) what other investments ( outside of real estate ) did you find suited you ? REITs ? Dividend paying stocks ? ETFs ? Annuities ? Covered calls ? Spreads ? Pref shares ? Pre-IPO stocks ? Private equity ? Why ?
P) what is your average or preferred $ allocation per deal ?