It depends on if the concrete is hard troweled... or not. If it's fairly porous (which is unlikely) then a good cleaning and sealing will be fine with most sealers. More than likely you would be wise to do a mild acid etch with muriatic acid and/or a good pressure washing at high pressure.
I know you want to keep the advice simple... there are so many variables with coating concrete. Next, there is the question of the sealer... Solventbased or Waterbased. This again is going to depend on the level of prep that you do. You're going to need just a little background to make this decision. First, most (in fact almost all) waterbased products are either emulsions or dispersions of acrylic resin. Don't tune this out yet... I promise it will all make sense if you read it all...
First, the acrylic resin that you want to protect your concrete is actually a solid. So, somehow that has to be turned into a liquid so it will fill the pores of your concrete and become a film. The challenge is that the solid acrylic is NOT water soluable... it won't dissolve in water. So, the acrylic must be dissolved in solvent, dispersed in water, or emulsified.
Dissolution in Solvent:
This is a pretty simple concept. You simply throw the solid resin into solvent, the solid resin dissolves, and is liquified so that it can form a film. You could liken this to throwing salt in water. The salt will dissolve and if you pour it out on your concrete and the water evaporates you will be left with salt.
Dispersion:
Basically a dispersion is solid particles suspended in something. So, imagine if you took a bunch of Feta Cheese and suspended it in water. The way that acrylic is dispersed in water is with force that breaks the resin apart. Then, the particles have to be stabilized with some kind of surfactant. The problem with most dispersions is that the surfactant doesn't leave the film and surfactants are very sensitive to water. Basically, a surfactant is like a soap. When you do your laundy you are using a surfactant that will suspend the dirt from your clothes in water and then evacuate the dirt with the water when it drains. Typically, the particles in a dispersion are kinda jagged like the picture...
Emulsion:
Basically, imagine that you melt the cheese and then stir it into boiling water with a wisk. Then, you keep wisking the water/cheese constantly until the water cools enough for the cheese to harden in little droplets in the water. These particles are nice and round... easily filling pores...
One of the most important considerations is that the sealer you use is 100% acrylic. Adding other materials like Vinyl Acetate will cheapen the formulation and greatly lower the durability. Stay away from Co-Polymers... The other consideration is that the acrylic is really small...
So, if you have large open pores then larger particles of acrylic (most waterbornes) are just fine. But, if they are not as large or open then your best odds of longevity are really small particles that will pack into the pores.
Coatings manufacturers have been trying for years to match the performance of solventbased sealers with waterborne formulations. It is only now that waterborne technologies have caught up and are overtaking the solventborne systems. It looks like Wolverine Coatings is the first company to commercialize a nanopolymer (really really really really small) waterbased sealer (AcryliSeal 3501).
So, if you have good open pores then the decision isn't that critical (if you are using 100% acrylic). If not... then get some solventbased (AcryliSeal 3401/ H&C Clear Sealer 23) since the odds are higher for success. (The H&C is only 23% solids... AcryliSeal is 28% solids). The H&C may be less expensive if you can find it close by. It takes more of it to get the same results as our solventbased sealer but you can probably buy more for what freight would be for this product.
OK... I've got to end this abruptly... It's 12:30 AM... How'd that happen?
Do you have any good pics of the concrete?
I just don't have that kind of coin. I had wanted to put something on it to keep the oil stains and whatnot from soaking in, but I guess I'm just destined to have a ****** looking floor. 
