What's the best grade of apartment complexes to invest in for income growth.

I have not used it in depth but it seems to have some neat features, and of course more if you want the paid version.

How would you explain to an investor on how to analyze their first apartment complex for purchase?

I like the search features: https://www.biggerpockets.com/search

I currently rent in an apartment complex so when my lease is up next May, I want to buy a triplex or four-plex (if I'm lucky) to start house Hacking.

Never the models with the extra whiz bang features because those are always the things that break and cost $$ to repair.

Check out the condo docs and find out how the price he's willing to sell it for compares with recent sales in the complex.

Stick with it, I'm not sure how not being a US citizen complicates investing in the states but I'm assuming it adds another layer of complexity, there is money to be made in the 'land of milk and honey'! 

It may not move very fast since there is lot of inventory sitting in your complex so price, condition and marketing will be key.

I like the search features: https://www.biggerpockets.com/searchUse the Bigger Pockets glossary to learn more about real estate terms that may be new to you: https://www.biggerpockets.com/rei/glossaryAlerts can be really helpful too: http://www.biggerpockets.com/alerts