Have a plan — and maintain it.
Once you choose investments that match your risk tolerance and decide how much money to commit to each asset class, review your plan every year to determine whether it is still on track.
Because stocks, bonds and cash tend to move in different cycles, you may find that the asset allocation you started with at the beginning of the year may not be the asset allocation you have on December 31. If any of your allocations have strayed from their targets you may want to bring them back into balance by trimming your largest positions and adding to the smaller.
This strategy, called rebalancing, is easy to do in a retirement account because there are no tax implications. For tips on rebalancing within a taxable account, consult a tax professional.