As they say in hockey "A good player goes where the puck is while a great player goes where the puck will be."

Anyone asking for money up-front should raise a red flag.Listen to the BP Podcasts, attend local REIA and if you can most likely find a mentor there for free.

Although I'm unsure of the specific niche I'll be assigned to, the group handles a diverse range of matters (construction, development, zoning, financing etc. etc.) for some of the biggest players in town. 

We have a super competitive market here in PDX and Vancouver and there are a few bigger players but the little mom and pop investors get their share of deals...

What other red flags have other investors seen that I should pay closer attention? 

I was thinking about going to join Keller Williams or possibly Red Door.

For example, a $5,000 mistake or unknown variable on an $80,000 ARV house can put you in the red.

He's a good guy-- and a fine guitar player too :)

Also depending on your relalionship with a title company they may write around these if your a big enough player.

As a real estate investor could be dealing with multiple sale transactions over time, having a real estate agent license could save the 3% of sale every time, however, i read that the seller being the agent could be a red flag for the buyer.