As a 23 yr old starting my first job and knowing I would be getting married within a year or so, I started 401k at 7% of my salary. Went up 2% with each raise and was quickly at the 15% max. I wish now that I would have started the Roth IRA sooner,
but oh well. 5% for me to Roth. If you never see the money, you will not ever miss it.

My advice is to
a. If you have limited options in market, do not chase the winner for a 6 month period. This is LONG term investing, so look at 10 year returns and make your decisions.

b. Don't worry when you see some big losses

c. Don't get too excited when you see some big gains.

Pretax 401k = you don't feel quite the sting on your check.

Post Tax Roth IRA = that sum beach hurts laugh