As others have said not setting fire to the bike or burning out the electrics is a good start but you might want to consider the effect of all those sparks on the cosmetics. It's not hard to get 'overspark' where molten metal sparks fly off and burn through paintwork / fuse with glass etc. Make sure stuff is covered if it's within spark range. Some welders will think of this, some won't.

When it comes to the actual repair, if it's just a steel bracket or something simple that's broken it shouldn't be too hard for a welder to fix but you might want to consider why it broke, and whether it really needs reinforcement. Push the ends together and weld around the crack may not be the best way to do it.

If you need to get something made from scratch welders that spend their day fixing bicycle frames at the side of the road (for example) may not have much of a grasp of materials science. I had to get a replacement kickstart fabricated in Mauritania and the welder made part of it from cast iron - something that's almost impossible to weld successfully. It kept snapping (and being rewelded) until (a week later) I rummaged through a welders workshop in Senegal, found some mild steel bar and had him use that.

If it's anything other than straightforward steel that breaks then good luck. You might find someone who can do stainless but any sort of alluminium alloy is going to need a specialist.

Lastly, don't assume that welding is the only way. You can 'splint' broken brackets and epoxy can often fix holes in castings. I've rejoined many parts with repair plates - drill a series of small holes on both sides of the break and screw a brace across them. When my kickstart was broken between welders I paid the local kids to bump start me. Actually, when the temperature went over 30C, that was better than having the kicker.