Two suggestions:
1. Put a portion of it in a savings account or ETF or index fund, that doesn't let you withdraw it for 3 months and add to that slowly. That way the temptation to spend doesn't get in the way.
2. I use a free app called Acorns that automatically invests it in a few different investment portfolios from conservative to aggressive. They make it easy to put in small deposits and work your way up. You can put in as little as $5 or as much as you want.
