I'm willing to invest into crytocurrencies but not sure how to start ones I'm ready to dive in. Shall I go through Bittrex, Coinbase or find a legit seller here in BTCtalk? What would be your advise?
You're not going to get any deal for your fiat currency on bittrex. They just don't deal with fiat at all.
Go through a legit seller on bitcointalk if I were you. Or use paxful. Both are going to mean high premiums, but at least you won't have any issues with verification or the exchange holding your funds for prolonged periods of time.
Obviously, store it in a wallet instead of exchange. Otherwise, your funds are not really yours but someone else's.
Wish you all the best.