As stated earlier there are reasons for the relative sparseness of male signals compared to female flirting signals.
Most men are interested perpetually in most women, and therefore male signals are generally designed to attract the attention of any females, rather than directed at one female in particular.
Male interest is basically always switched on and ready to respond to opportunity when female availability and interest are signalled and noticed.
Men believe they take the lead, but actually mostly women do.
Male signals of interest in females essentially follow normal body language rules, for example widening eyes, dilated pupils, forward leaning, prolonged direct eye contact, active listening reactions, and these come into play once eye contact and/or proximity is established.
The most prevalent signals males use to announce their availability and attract female attention are summarised below. Under many circumstances these might be categorised under the headings 'pathetic' or 'amusing'. The male of the species, despite a couple of million years of evolution, has yet to develop much subtle body language in this area.
posturing - erect stance, chest out, shoulders back, stomach in.
wide stance - legs apart (standing or sitting) - to increase size.
cowboy stance - thumbs in belt loops, fingers pointing to genital area.
hands in pockets - thumbs out and pointing to genitals.
'chest-thumping' - a metaphor describing various male antics designed to draw attention to themselves, often involving play-punching or wresting other males, laughing too loudly, head-tossing, acting the fool, etc.
room scanning - males who are available and looking for females tend to scan the room, partly to look for available females, but also to indicate they are available themselves.
dress - clothing: style, fit, cleanliness, etc - is all an extension of personality and is therefore part of body language.
preening and grooming - adjusting clothes, ties, cuffs, sleeves, tugging at trouser crotch, running hands through or over hair, etc.
smell - certain smells are attractive to females but it's a complex and highly personal area yet to be understood well. Answers on a postcard please.
tattoos - here's an interesting one, commonly ignored in conventional body language flirting guides. Tattoos have dramatically altered in society's perceptions in the past generation. Previously considered indicative of lower class, lower intellect, sailors, soldiers, builders, etc., nowadays they are everywhere on everyone. Tattoos have been a significant part of human customs for thousands of years. They are decorative, and also (in evolutionary terms) suggested strength and machismo, since the process of obtaining them was painful and even life-threatening. Certain females are attracted by tattoos on men, especially extensive markings. It's a drastic step to improve one's love life, but worthy of note, because the subject is not as simple and negative as traditionally regarded. Tattoos are significant attention-grabbers, and given the variety of subjects featured, also provide interesting talking points.
body piercings - again more complex than traditionally considered, piercings do attract attention and signify the wearer to be different.
dancing - dancing, in a suitable place of course, has for thousands of years been an opportunity for males and females to display their physical and sexual potential. With the exception perhaps of pogo-ing and head-banging most dance styles replicate sexual movements - lots of rhythmic hip and leg work, contorted facial expressions, sweating and occasional grunting, etc. For those blessed with a level of coordination dancing offers an effective way of attracting attention, especially in crowded competitive situations. For the less rhythmic, the lesson is to find a different environment.