In general, how do online ratings compare to USCF ratings? I realize that there is no set rule, I am just looking for any general guidlines

There really aren't any. Any attempts to formulate some +200/-100 rule is murky at best.

There is some, albeit poor correlation that high online ratings indicate a comparable rating strength (only for live chess at slow time controls!) if said person were to be playing on the USCF.

Though the reverse direction seems to be a bit more promising.  A strong USCF player tends to perform just as well at live chess at SLOW time controls on usually any chess server.

Trying to compare the ratings of some XYZ Chess server's One-move-a-day-chess (Online chess) or blitz/bullet/anything-but-slow to USCF tournament play seems like a waste of time.

what is considered slow time controls for live chess? would that be standard live  rating?

From a USCF standpoint, anything above a G/29 (With or without a time-delay) is considered sufficient for a slow game. 

So 15 mins doesn't count, but 30 mins does ... though the chess.com live rating makes no such distinction => another reason why trying to compare the two very different rating systems is murky!

Also, curious ... have you or are you considering playing OTB chess under the USCF federation?  

ok then none of these ratings on chess.com are helpful

I am rated 1504 and rapidly rising, but since I play more on here than in real tournaments I was trying to get an idea of my acual strength

chess.com ratings are probably at least 300 points higher than USCF

Thats what I thought, or about 200 I heard, but then It really seems to differ depending on the number of games and focus. Some people are rated lower online than in person. It is going to take more research I think haha

The idea that populations with substantial overlap, playing the same game, and rated by two similar but slightly different systems, won't be predictably correlated, can only be true if one or both of the two rating systems is an ineffective predictor.  Since this is likely not the case, there is almost certainly a strong and predictable correlation if anyone would bother to do the analysis.  In my limited experience, the chess.com ratings are rather close to the USCF ratings, and if anything might be lower.

How to compare ratings

Higher ratings > lower ratings.

Well people do tend to say it's +/- 100 or 200 points, it's just the individual has to be careful that they don't immediately believe "I must be one of those who's underrated!" so it comes with the warning that it's "murky" as shivsky said.

I think nearly all players believe they're underrated heh.

Yes, it does seem most people think they are underrated.  Just as most people rated below 1500 think they are too advanced for beginner books and want to study Kotov.

Your way of stating it "+/- 200" seems much more correct to me than saying just "- 200".  To me, when I get over 1350 on chess.com, I start to feel like the opponent is really better than me and I'm barely hanging on.  In USCF, I start to feel like that about the same point.  So that is why I think they are about the same, and not too different.

I tend to think my USCF should be higher too... and of course I could give all sorts of reasons I believe this is true... but I remind myself so do nearly all other players, so it is what it is until I go to more tournaments and prove otherwise