As suggested, use the widest radius turnout you can fit in. This makes the transition from one loop to the other as gradual as possible. Not only lessens de-railment issues but looks better as well.
I use fastrack, and have upper and lower loops connected. I could only use 048 turnouts, as my connection to the lower loop is part of an 048 turn but I was able to have a straight section between the turnouts, which helps in the transition. The photo shows how I made my connection.
REV
The tank train is actually running on my "Lower Loop" and the WP Diesel is sitting on a yard track which is part ot the upper section.