Currently i'm using something like the following:

LineSeries lineSeries = (LineSeries)parentChart.Series.Add(SeriesType.Line);
lineSeries.Name = seriesName;
lineSeries.DataLabels.Mode = DataLabelsMode.None;
lineSeries.Markers.Style = PointStyle.Cone;
lineSeries.Appearance.FillMode = AppearanceFillMode.Series;
lineSeries.Appearance.LineMode = AppearanceLineMode.Series;
lineSeries.LineFillEffect.SetSolidColor(colorOfLine);
lineSeries.Legend.Mode = SeriesLegendMode.Series;

Right now, I can see the multiple lines but they are all black, even in the legend.
I feel like I'm really missing something here but according to the document, this should work.
What am i doing wrong? 

The LineFillEffect is for the inside part of the line when the LineStyle is set to something other than Line (e.g. Tape) and the chart is set to 3D.  What you need is to set the LineBorder property.

e.g.:

lineSeries.LineBorder.Color = Color.DodgerBlue;

Oh ok. so that solves the problem of line colors.
But one other thing that I've been having trouble with is setting markers on these lines.
Here is what I am doing currently:

lineSeries.Markers.Style = PointStyle.Sphere;

But nothing show up for the data points.
What is the proper way to set different Marker shapes?

Hm. Never mind, it's now working.
 

lineSeries.Markers.Border.Color = colorOfLine;
lineSeries.Markers.Visible = true;
lineSeries.Markers.Style = PointStyle.Sphere;

This did the trick. Not sure why it wasn't working before though.