OK, I'll analyse those two songs in depth ...
One Private Moment
This song has potential to be successful, but I think you "develop" it too slow and too sparsely. It's got a good-enough melody to be a hit, but I think the arrangement needs work. Details:
-- The opening guitar riff. This is a decent opener, but my feeling is that it could be better. For starters, I think it would be better played with an electric guitar rather than an Ovation (or whatever similar amplified-acoustic you're using). Either that or use a "pure" acoustic guitar (though I think electric would be better). It might even work better on a keyboard, maybe. Also, you start out with the short synthesizer segment, but then it slowly disappears after the guitar kicks in. I would suggest to not do that - instead *overlay* the guitar on top of the synthesizer - this builds up drama for the listener (and do something else with the synthesizer after the guitar kicks in). And speaking of "layering", around the 10-11 second mark when the riff switches to a different chord, it would be nice to add yet another layer - either a counter-riff, bass line, some drums or even just a rhythm guitar part. Study Tame Impala's
It's Not Meant to Be. This is a great example of (an extended,) layered introduction. The bass line is particularly catchy. Notice how the song builds up. I can tell Kevin Parker has *really* done his homework and studied a lot of pop/rock music just by listening to that one song - he presses all the right buttons and clearly knows what he's doing.
-- Around the 38 second mark there is a vocal pause of empty space which seems to come out of nowhere and is not filled with anything. I think it would sound better with either: 1) a complete, 100% pause in the music, or 2) fill it with yet another new layer of ... something. You're about to introduce a new verse - set up the listener for that by either pausing altogether or introducing something new. Or both.
-- Second verse. Follow through with what I suggested just above. Don't just repeat the first verse,
add something to it. New instrumental layers, a harmony, maybe even change keys.
-- The verse starting with "Pressure." Here you *finally* introduce a new layer. This is what you should have done at least 1 verse prior, if not somewhere in the introduction. But by now you should be taking the listener into some whole new realm. It's nicer here than in the introduction, but by now the listener should be surrounded by sound, with at least a couple guitars, bass, maybe a keyboard and maybe some harmonies. Then, maybe later in the song, drop *all* of that as a pause and start all over again.
-- Basically, the arrangement you've got near the end of the song is similar to what you should have somewhere about halfway through the song. Then, maybe 2/3 through the song, throw the listener a wrench by either blowing them out with sound overload at the end, or by completely dropping an already-developed overload by going back to the original sparse arrangement.
-- As one final comment, I realize you might not have had the equipment to do it, but I think your voice (or your band-mate's) voice would sound better double-tracked.
Welcome to the Party
Not quite sure what to say about this one. It seems a little more developed than the first song, but it still seems to need something else. A bit disco-esque. I like the synthesizer solo, but I think if you worked on the refrain/chorus and gave it a "zippier" melody you'd have a better song. Interesting end, though. That works pretty good.
A good way to learn how to be a good songwriter is to study how other good songwriters went about it. Here's an interview I always liked where Paul Simon is talking with Dick Cavett about his approach to songwriting. Notice how he's interested in what the listener is expecting (especially the part starting around 3:30 or so):
Anyway, don't take all this to be critical, I'm just giving what I hope are helpful suggestions.
