There is some great advice that has been given to you by my colleagues on this post. I would add two more items to think about:
1) Hyperlocal knowledge of the neighborhoods in question allow your agent to most effectively assist you in both endeavors. There are certain nuances in every neighborhood, that if you know about them, can greatly benefit you when selling and/or buying real estate. BTW, if you aren't already working with an agent, I would be honored to assist you...my office is in West Hollywood at Santa Monica and La Cienega Blvds. and I own property and live in Santa Monica.
2) Certainty of closing is critical in every real estate deal in today's market; especially in your position where you are selling your primary residence and looking to purchase a new home as quickly as possible. Your agent needs to put you in the best possible position to close quickly with as few uncertainties as possible for the sale of your WeHo condo AND make your offer as strong as possible so that it is placed on top of the stack of offers for your new home in Santa Monica. I have been doing this for my clients and myself for the past 19+ years.
I would also like to add that Sergey's suggestion regarding a 1031 exchange is, in my opinion, an absolute must. I have personally done this almost a dozen times for all of my properties and would be more than happy to share my experiences and refer/assist you in this smart "tax-saving" strategy.
I wish you the best of luck! This is an exciting time for you and I would love to help you realize your goals. Let's meet at Earth Bar to discuss your opportunities.
Austin Chen, REALTORÂ®
Real Estate Investment Specialist
DRE #: 01898306
Office: 323.902.SOLD (7653)