Clear labelling gray-scale plots

Question

I am plotting a number of functions (at least 4 in one plot) with a legend. Needless to say, it is important that it is clear from the legend which line belongs to which function. I tried to play around with the PlotStyle, but I'm not getting them to look all that different. The paper it will be published in demands grey-scale pictures, so I can't use different colours.

I was hoping to use PlotMarkers instead, but I found that these only exist within the ListPlot but not in Plot. In theory I could overlay a Plot with a ListPlot, but then it wouldn't show in the legend. What is the best way to add the markers in both the plot and the legend?

This is a minimal working example of something to which I'd to add PlotMarkers.

Needs["PlotLegends`"];
Plot[{Sin[x], Sin[x + π/4], Sin[x + π/2], Sin[x + 3π/4]}, {x, 0, 2π},
     PlotLegend -> {"#1", "#2", "#3", "#4"},
     PlotStyle -> {DotDashed, Dashed, Dashing[0.01], Dotted}]

Answer 1

If you have the functions, you can always make a ListPlot

f1[x_] := Sin[x];
f2[x_] := Sin[x + \[Pi]/4];
f3[x_] := Sin[x + \[Pi]/2];
f4[x_] := Sin[x + 3 \[Pi]/4];
(*some arbitrary functions*)

(*create table from a function*)
dataf[f_, xmin_, xmax_, ndata_] := Table[{x, f[x]}, {x, xmin, xmax, (xmax - xmin)/ndata}];

Needs["PlotLegends`"];
ListPlot[{dataf[f1, 0, 2 \[Pi], 20], dataf[f2, 0.01, 2 \[Pi], 20],
dataf[f3, 0.02, 2 \[Pi], 20], dataf[f4, 0.03, 2 \[Pi], 20]}, 
PlotLegend -> {"f1", "f2", "f3", "f4"},LegendPosition -> {1.1, -0.4},
LegendShadow -> False, Joined -> {True, False, True, False},
PlotMarkers -> Automatic]

It will give you this

Answer 2

  h = Graphics[{Black, #1}, PlotRange -> #2] &; 

  ListPlot[Transpose@Table[{Sin[x], 
                            Sin[x + \[Pi]/4], 
                            Sin[x + \[Pi]/2], 
                            Sin[x + 3 \[Pi]/4]}, {x, 0, 2 \[Pi], .1}], 
           PlotLegend -> {"#1", "#2", "#3", "#4"}, Joined -> True, 
           PlotStyle -> Directive@{Black, Thick},  ImageSize -> 500,
           PlotMarkers -> {{h[Disk[], 1], .04}, {h[Disk[], 2], 0.01}, 
                           {h[Rectangle[{-1, -1}, {1, 1}], .5], .04}, 
                           {h[{Thick, 
                               Line[{{0, 0}, {0, 10}}]}, {{-1, 1}, {0, 10}}], .05}}]