Recon
One thing with recon with Red Alert, is that there is no fog of war. Once your unit explores the map, you'll always see it (unless gap generators go up). In War2, you could recon the entire map and it wouldn't do you much good (except for revealing the terrain). Take advantage of the non-fog of war in RA.
Beginning- If you start off with any units at the beginning of the game, use them as recon so you can find a suitable spot for your MCV to plant down. Let's say you start out with no units. Simply plant your MCV, and quickly make a powerplant. Before you click on the Ore Refinery icon, make a barracks first. While you're building the ore refinery, start reconing the entire map with riflemen. Not only should you descover what the map looks like, but you should find the enemy base. Besides from riflemen, a lone tank can be a great scounting unit. Especially if the enemy is soviet, go inside their base with a tank. It may be futile to do this if the enemy is allied, since they'll be putting up gap generators as fast as possible.
Its funny how some people don't make a barracks until after making an ore refinery. Unless you start off with hardly any money (which is rare) always make a barracks before an ore refinery. If you discover that your opponent doesn't do this, infantry rush him :)
Middle- Don't be stupid. Once you get on water use gunboats to explore NOT cruisers. I think its funny when the player is exploring the water with his cruiser when my subs come out of nowehere and waste him. Likewise, don't explore with an MCV. You may think I'm sputtering out nonsense but people ACTUALLY do this! Once someone's MCV drove right into my tank army. Aside from using some basic common sense, use your spyplane to explore the hard to reach areas (such as the enemy's base :). Paratroopers can make good recon units as well.
End- Until gap generators go up, recon is easy. Spy planes can reveal the gap generated shrouds, but not too long. Sometimes you'll see their base for a split second before the shroud reappears. So instead, make a tank sacrifice to the RA god to help you. In other words, use a tank or two to go into the gap generated area to see what you need (this works alot better if you iron curtain them). If that doesn't work, use your paratroopers. If your plane doesn't get shot down, your paratroopers should reveal enough of the area so you can send in your migs.
If you're allied, recon is easy. Just make a GPS satellite. Some people are used to selling their soviet tech centers, and I think its funny that once someone gets their GPS satellite up they sell their tech center. They think once they get their satellite up that they don't need their tech center anymore. Well, WRONG! They usually learn it the hard way :)