Wasp strips : My suggestion would be (and this is the way I would do it) firstly to spray the ends black with "Plastikote" aerosol (available from DIY stores / Wilkinsons, etc). I used this paint on my LNER N5, Midland Johnson 2F and LMS Fowler 4F. It is easy to get a good smooth finish, is very quick drying (five minutes per coat when sprayed in light coats) and, most importantly, when dry and thoroughly hardened (leave at least a day to harden) is unaffected by enamel thinners/white spirit, etc. (but it can be removed with cellulose thinners if necessary).
Next apply strips of masking tape and apply the stripes with yellow enamel (e.g. Humbrol).
If there are any problems with "bleeding" you can wipe away the yellow using enamel thinners (but not cellulose thinners) and try again without any harm to the black base coat.
You could use acrylic yellow instead of enamel, which can be wiped away (while still wet) with a water-soaked cloth but it dries extremely quickly (a few minutes...after which it is very difficult to remove). Enamel usually takes much longer to dry, leaving more time to make adjustments.
I use "Plastikote" on wagons for the roofs (white or grey) and underframes (black) before spraying the sides/ends with the body colour, then any spray which creeps under the edges of the masking tape is easily removed from the white, grey, black parts.
Alternative would be to spray end black, get a sheet of waterslide decal paper, paint it yellow, cut into strips and apply as you would any other transfer. Whether it would prove successful will largely depend upon how flat/detail free is the surface to which the strips are applied.