Sun protection should be a year round thing, but especially in the spring and summer months. My favorite sunblock is the Neutrongena Sport Face and the Sport for body. Another good defense against the sun when riding or running are arm coolers... similar to this. Of course sunglasses and hats are smart to wear as well.
This is a good time of the year to get in for lactate testing. Call your local facility to get your zones dialed in for the season. Also, now is a good time to get a tune up on your bike and if there's any issues you are having on rides to get a custom fit. Have a gait analysis done, with the season just starting it's not too late to get this in. Getting in with a dietitian to have your RMR and body fat measured will help to dial in your race nutrition.
Go through and inventory all your tri items. Spring clean your tri gear. Inventory your training and race clothes, see how worn your running shoes are, check to see if any of your nutrition products are low or expired, check the wear on your swim suits, are your goggles falling apart, etc.
Now is the time to finalize your race schedule and start registering for races if you haven't already signed up for them. A lot of races fill up quickly. Some you have to register for a full year in advance. Many races are now offering race registration insurance. Buy it!!!! You never know what could happen especially when you have to register for a race so far in advance.
This is also a good time to go over your annual training plan or if you have a coach meet with them and go over it. See if you have any changes you want to make before the season really starts. It makes things easier for you and the coach if there aren't a lot of intentional changes to the plan during the season.
If you are new to triathlon, find some tri groups close to you. Great way to find training partners and find out the best places to swim, bike, and run. Also, you can pick other athletes' brains about favorite races.
Cheers to a great race season!!